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Improvement and extension of EnKF algorithm (EnKS)
authorJean-Philippe ARGAUD <jean-philippe.argaud@edf.fr>
Sun, 28 Mar 2021 18:19:57 +0000 (20:19 +0200)
committerJean-Philippe ARGAUD <jean-philippe.argaud@edf.fr>
Sun, 28 Mar 2021 18:19:57 +0000 (20:19 +0200)
src/daComposant/daAlgorithms/EnsembleKalmanFilter.py
src/daComposant/daCore/BasicObjects.py
src/daComposant/daCore/NumericObjects.py

index cd43a13df9362f68c46abf1081938a11a5da4915..4433902850193964ff095cea14fd08f2008fe6ea 100644 (file)
@@ -39,6 +39,7 @@ class ElementaryAlgorithm(BasicObjects.Algorithm):
                 "ETKF-N",
                 "MLEF",
                 "IEnKF",
+                "EnKS",
                 ],
             listadv  = [
                 "StochasticEnKF",
@@ -53,6 +54,7 @@ class ElementaryAlgorithm(BasicObjects.Algorithm):
                 "MLEF-B",
                 "IEnKF-T",
                 "IEnKF-B",
+                "EnKS-KFF",
                 "IEKF",
                 ],
             )
@@ -97,17 +99,10 @@ class ElementaryAlgorithm(BasicObjects.Algorithm):
             )
         self.defineRequiredParameter(
             name     = "SmootherLagL",
-            default  = 1,
+            default  = 0,
             typecast = int,
             message  = "Nombre d'intervalles de temps de lissage dans le passé",
-            minval   = 1,
-            )
-        self.defineRequiredParameter(
-            name     = "SmootherShiftS",
-            default  = 1,
-            typecast = int,
-            message  = "Nombre d'intervalles de temps de décalage de lissage",
-            minval   = 1,
+            minval   = 0,
             )
         self.defineRequiredParameter(
             name     = "SetSeed",
@@ -151,7 +146,6 @@ class ElementaryAlgorithm(BasicObjects.Algorithm):
                 ],
             listadv  = [
                 "CurrentEnsembleState",
-                "LastEnsembleForecastState",
                 ],
             )
         self.requireInputArguments(
@@ -213,6 +207,11 @@ class ElementaryAlgorithm(BasicObjects.Algorithm):
             NumericObjects.ienkf(self, Xb, Y, U, HO, EM, CM, R, B, Q, BnotT=True)
         #
         #--------------------------
+        # Default EnKS = EnKS-KFF
+        elif self._parameters["Variant"] in ["EnKS-KFF", "EnKS"]:
+            NumericObjects.enks(self, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="EnKS16-KalmanFilterFormula")
+        #
+        #--------------------------
         else:
             raise ValueError("Error in Variant name: %s"%self._parameters["Variant"])
         #
index c5f2cb06906ab92c63d106819f77bcff707251d7..1a37c00ad32382a8305f1e9aee4cec5539d09ad4 100644 (file)
@@ -677,7 +677,6 @@ class Algorithm(object):
         self.StoredVariables["JacobianMatrixAtCurrentState"]         = Persistence.OneMatrix(name = "JacobianMatrixAtCurrentState")
         self.StoredVariables["JacobianMatrixAtOptimum"]              = Persistence.OneMatrix(name = "JacobianMatrixAtOptimum")
         self.StoredVariables["KalmanGainAtOptimum"]                  = Persistence.OneMatrix(name = "KalmanGainAtOptimum")
-        self.StoredVariables["LastEnsembleForecastState"]            = Persistence.OneMatrix(name = "LastEnsembleForecastState")
         self.StoredVariables["MahalanobisConsistency"]               = Persistence.OneScalar(name = "MahalanobisConsistency")
         self.StoredVariables["OMA"]                                  = Persistence.OneVector(name = "OMA")
         self.StoredVariables["OMB"]                                  = Persistence.OneVector(name = "OMB")
index 2468049bdaaef1f02be74d3eb80940b313a68c6a..5089c21f3ef060896e8739797cad63995898096f 100644 (file)
@@ -443,84 +443,6 @@ class FDApproximation(object):
             if self.__mfEnabled: return [_HaY.A1,]
             else:                return _HaY.A1
 
-# ==============================================================================
-def mmqr(
-        func     = None,
-        x0       = None,
-        fprime   = None,
-        bounds   = None,
-        quantile = 0.5,
-        maxfun   = 15000,
-        toler    = 1.e-06,
-        y        = None,
-        ):
-    """
-    Implémentation informatique de l'algorithme MMQR, basée sur la publication :
-    David R. Hunter, Kenneth Lange, "Quantile Regression via an MM Algorithm",
-    Journal of Computational and Graphical Statistics, 9, 1, pp.60-77, 2000.
-    """
-    #
-    # Recuperation des donnees et informations initiales
-    # --------------------------------------------------
-    variables = numpy.ravel( x0 )
-    mesures   = numpy.ravel( y )
-    increment = sys.float_info[0]
-    p         = variables.size
-    n         = mesures.size
-    quantile  = float(quantile)
-    #
-    # Calcul des parametres du MM
-    # ---------------------------
-    tn      = float(toler) / n
-    e0      = -tn / math.log(tn)
-    epsilon = (e0-tn)/(1+math.log(e0))
-    #
-    # Calculs d'initialisation
-    # ------------------------
-    residus  = mesures - numpy.ravel( func( variables ) )
-    poids    = 1./(epsilon+numpy.abs(residus))
-    veps     = 1. - 2. * quantile - residus * poids
-    lastsurrogate = -numpy.sum(residus*veps) - (1.-2.*quantile)*numpy.sum(residus)
-    iteration = 0
-    #
-    # Recherche iterative
-    # -------------------
-    while (increment > toler) and (iteration < maxfun) :
-        iteration += 1
-        #
-        Derivees  = numpy.array(fprime(variables))
-        Derivees  = Derivees.reshape(n,p) # Necessaire pour remettre en place la matrice si elle passe par des tuyaux YACS
-        DeriveesT = Derivees.transpose()
-        M         =   numpy.dot( DeriveesT , (numpy.array(numpy.matrix(p*[poids,]).T)*Derivees) )
-        SM        =   numpy.transpose(numpy.dot( DeriveesT , veps ))
-        step      = - numpy.linalg.lstsq( M, SM, rcond=-1 )[0]
-        #
-        variables = variables + step
-        if bounds is not None:
-            # Attention : boucle infinie à éviter si un intervalle est trop petit
-            while( (variables < numpy.ravel(numpy.asmatrix(bounds)[:,0])).any() or (variables > numpy.ravel(numpy.asmatrix(bounds)[:,1])).any() ):
-                step      = step/2.
-                variables = variables - step
-        residus   = mesures - numpy.ravel( func(variables) )
-        surrogate = numpy.sum(residus**2 * poids) + (4.*quantile-2.) * numpy.sum(residus)
-        #
-        while ( (surrogate > lastsurrogate) and ( max(list(numpy.abs(step))) > 1.e-16 ) ) :
-            step      = step/2.
-            variables = variables - step
-            residus   = mesures - numpy.ravel( func(variables) )
-            surrogate = numpy.sum(residus**2 * poids) + (4.*quantile-2.) * numpy.sum(residus)
-        #
-        increment     = lastsurrogate-surrogate
-        poids         = 1./(epsilon+numpy.abs(residus))
-        veps          = 1. - 2. * quantile - residus * poids
-        lastsurrogate = -numpy.sum(residus * veps) - (1.-2.*quantile)*numpy.sum(residus)
-    #
-    # Mesure d'écart
-    # --------------
-    Ecart = quantile * numpy.sum(residus) - numpy.sum( residus[residus<0] )
-    #
-    return variables, Ecart, [n,p,iteration,increment,0]
-
 # ==============================================================================
 def EnsembleOfCenteredPerturbations( _bgcenter, _bgcovariance, _nbmembers ):
     "Génération d'un ensemble de taille _nbmembers-1 d'états aléatoires centrés"
@@ -596,6 +518,7 @@ def EnsembleErrorCovariance( Ensemble ):
     "Renvoie la covariance d'ensemble"
     __Anomalies = EnsembleOfAnomalies( Ensemble )
     __n, __m = numpy.asarray(__Anomalies).shape
+    # Estimation empirique
     __Covariance = (__Anomalies @ __Anomalies.T) / (__m-1)
     # Assure la symétrie
     __Covariance = (__Covariance + __Covariance.T) * 0.5
@@ -671,601 +594,735 @@ def CovarianceInflation(
     return OutputCovOrEns
 
 # ==============================================================================
-def multi3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, oneCycle):
+def enks(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="EnKS16-KalmanFilterFormula"):
     """
-    3DVAR multi-pas et multi-méthodes
+    EnKS
     """
     #
-    # Initialisation
-    # --------------
-    Xn = numpy.ravel(Xb).reshape((-1,1))
+    # Initialisations
+    # ---------------
+    #
+    # Opérateurs
+    H = HO["Direct"].appliedControledFormTo
     #
     if selfA._parameters["EstimationOf"] == "State":
-        M = EM["Direct"].appliedTo
-        #
-        if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
-            selfA.StoredVariables["Analysis"].store( Xn )
-            if selfA._toStore("APosterioriCovariance"):
-                if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(Xn.size)
-                else:                         Pn = B
-                selfA.StoredVariables["APosterioriCovariance"].store( Pn )
-            if selfA._toStore("ForecastState"):
-                selfA.StoredVariables["ForecastState"].store( Xn )
+        M = EM["Direct"].appliedControledFormTo
     #
-    if hasattr(Y,"stepnumber"):
-        duration = Y.stepnumber()
+    if CM is not None and "Tangent" in CM and U is not None:
+        Cm = CM["Tangent"].asMatrix(Xb)
     else:
-        duration = 2
+        Cm = None
     #
-    # Multi-pas
-    # ---------
-    for step in range(duration-1):
+    # Précalcul des inversions de B et R
+    RIdemi = R.sqrtmI()
+    #
+    LagL = selfA._parameters["SmootherLagL"]
+    if (not hasattr(Y,"store")) or (not hasattr(Y,"stepnumber")):
+        raise ValueError("Fixed-lag smoother requires a series of observation")
+    if Y.stepnumber() < LagL:
+        raise ValueError("Fixed-lag smoother requires a series of observation greater then the lag L")
+    duration = Y.stepnumber()
+    __p = numpy.cumprod(Y.shape())[-1]
+    __n = Xb.size
+    __m = selfA._parameters["NumberOfMembers"]
+    #
+    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
+    else:                         Pn = B
+    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
+    else:                         Qn = Q
+    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
+        selfA.StoredVariables["Analysis"].store( Xb )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            covarianceXa = Pn
+    #
+    # Calcul direct initial (on privilégie la mémorisation au recalcul)
+    __seed = numpy.random.get_state()
+    selfB = copy.deepcopy(selfA)
+    selfB._parameters["StoreSupplementaryCalculations"] = ["CurrentEnsembleState"]
+    if VariantM == "EnKS16-KalmanFilterFormula":
+        etkf(selfB, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM = "KalmanFilterFormula")
+    else:
+        raise ValueError("VariantM has to be chosen in the authorized methods list.")
+    if LagL > 0:
+        EL  = selfB.StoredVariables["CurrentEnsembleState"][LagL-1]
+    else:
+        EL = EnsembleOfBackgroundPerturbations( Xb, None, __m ) # Cf. etkf
+    selfA._parameters["SetSeed"] = numpy.random.set_state(__seed)
+    #
+    for step in range(LagL,duration-1):
+        #
+        sEL = selfB.StoredVariables["CurrentEnsembleState"][step+1-LagL:step+1]
+        sEL.append(None)
+        #
         if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((-1,1))
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            Ynpu = numpy.ravel( Y ).reshape((-1,1))
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
         #
-        if selfA._parameters["EstimationOf"] == "State": # Forecast
-            Xn = selfA.StoredVariables["Analysis"][-1]
-            Xn_predicted = M( Xn )
-            if selfA._toStore("ForecastState"):
-                selfA.StoredVariables["ForecastState"].store( Xn_predicted )
-        elif selfA._parameters["EstimationOf"] == "Parameters": # No forecast
-            # --- > Par principe, M = Id, Q = 0
-            Xn_predicted = Xn
-        Xn_predicted = numpy.ravel(Xn_predicted).reshape((-1,1))
+        if U is not None:
+            if hasattr(U,"store") and len(U)>1:
+                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
+            elif hasattr(U,"store") and len(U)==1:
+                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
+            else:
+                Un = numpy.asmatrix(numpy.ravel( U )).T
+        else:
+            Un = None
         #
-        oneCycle(selfA, Xn_predicted, Ynpu, U, HO, None, None, R, B, None)
+        #--------------------------
+        if VariantM == "EnKS16-KalmanFilterFormula":
+            if selfA._parameters["EstimationOf"] == "State": # Forecast
+                EL = M( [(EL[:,i], Un) for i in range(__m)],
+                    argsAsSerie = True,
+                    returnSerieAsArrayMatrix = True )
+                EL = EL + numpy.random.multivariate_normal(numpy.zeros(__n), Qn, size=__m).T
+                EZ = H( [(EL[:,i], Un) for i in range(__m)],
+                    argsAsSerie = True,
+                    returnSerieAsArrayMatrix = True )
+                if Cm is not None and Un is not None: # Attention : si Cm est aussi dans M, doublon !
+                    Cm = Cm.reshape(__n,Un.size) # ADAO & check shape
+                    EZ = EZ + Cm * Un
+            elif selfA._parameters["EstimationOf"] == "Parameters":
+                # --- > Par principe, M = Id, Q = 0
+                EZ = H( [(EL[:,i], Un) for i in range(__m)],
+                    argsAsSerie = True,
+                    returnSerieAsArrayMatrix = True )
+            #
+            vEm   = EL.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+            vZm   = EZ.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
+            #
+            mS    = RIdemi @ EnsembleOfAnomalies( EZ, vZm, 1./math.sqrt(__m-1) )
+            delta = RIdemi @ ( Ynpu - vZm )
+            mT    = numpy.linalg.inv( numpy.identity(__m) + mS.T @ mS )
+            vw    = mT @ mS.T @ delta
+            #
+            Tdemi = numpy.real(scipy.linalg.sqrtm(mT))
+            mU    = numpy.identity(__m)
+            wTU   = (vw.reshape((__m,1)) + math.sqrt(__m-1) * Tdemi @ mU)
+            #
+            EX    = EnsembleOfAnomalies( EL, vEm, 1./math.sqrt(__m-1) )
+            EL    = vEm + EX @ wTU
+            #
+            sEL[LagL] = EL
+            for irl in range(LagL): # Lissage des L précédentes analysis
+                vEm = sEL[irl].mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+                EX = EnsembleOfAnomalies( sEL[irl], vEm, 1./math.sqrt(__m-1) )
+                sEL[irl] = vEm + EX @ wTU
+            #
+            # Conservation de l'analyse retrospective d'ordre 0 avant rotation
+            Xa = sEL[0].mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+            if selfA._toStore("APosterioriCovariance"):
+                EXn = sEL[0]
+            #
+            for irl in range(LagL):
+                sEL[irl] = sEL[irl+1]
+            sEL[LagL] = None
+        #--------------------------
+        else:
+            raise ValueError("VariantM has to be chosen in the authorized methods list.")
+        #
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        selfA.StoredVariables["Analysis"].store( Xa )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(EXn) )
+    #
+    # Stockage des dernières analyses incomplètement remises à jour
+    for irl in range(LagL):
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        Xa = sEL[irl].mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+        selfA.StoredVariables["Analysis"].store( Xa )
     #
     return 0
 
 # ==============================================================================
-def std3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     """
-    3DVAR
+    Ensemble-Transform EnKF
     """
-    #
-    # Initialisations
-    # ---------------
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA._parameters["StoreInternalVariables"] = True
     #
     # Opérateurs
-    Hm = HO["Direct"].appliedTo
-    Ha = HO["Adjoint"].appliedInXTo
+    # ----------
+    H = HO["Direct"].appliedControledFormTo
     #
-    # Utilisation éventuelle d'un vecteur H(Xb) précalculé
-    if HO["AppliedInX"] is not None and "HXb" in HO["AppliedInX"]:
-        HXb = Hm( Xb, HO["AppliedInX"]["HXb"] )
+    if selfA._parameters["EstimationOf"] == "State":
+        M = EM["Direct"].appliedControledFormTo
+    #
+    if CM is not None and "Tangent" in CM and U is not None:
+        Cm = CM["Tangent"].asMatrix(Xb)
     else:
-        HXb = Hm( Xb )
-    HXb = numpy.asmatrix(numpy.ravel( HXb )).T
-    if Y.size != HXb.size:
-        raise ValueError("The size %i of observations Y and %i of observed calculation H(X) are different, they have to be identical."%(Y.size,HXb.size))
-    if max(Y.shape) != max(HXb.shape):
-        raise ValueError("The shapes %s of observations Y and %s of observed calculation H(X) are different, they have to be identical."%(Y.shape,HXb.shape))
+        Cm = None
     #
-    if selfA._toStore("JacobianMatrixAtBackground"):
-        HtMb = HO["Tangent"].asMatrix(ValueForMethodForm = Xb)
-        HtMb = HtMb.reshape(Y.size,Xb.size) # ADAO & check shape
-        selfA.StoredVariables["JacobianMatrixAtBackground"].store( HtMb )
+    # Nombre de pas identique au nombre de pas d'observations
+    # -------------------------------------------------------
+    if hasattr(Y,"stepnumber"):
+        duration = Y.stepnumber()
+        __p = numpy.cumprod(Y.shape())[-1]
+    else:
+        duration = 2
+        __p = numpy.array(Y).size
     #
     # Précalcul des inversions de B et R
-    BI = B.getI()
-    RI = R.getI()
+    # ----------------------------------
+    if selfA._parameters["StoreInternalVariables"] \
+        or selfA._toStore("CostFunctionJ") \
+        or selfA._toStore("CostFunctionJb") \
+        or selfA._toStore("CostFunctionJo") \
+        or selfA._toStore("CurrentOptimum") \
+        or selfA._toStore("APosterioriCovariance"):
+        BI = B.getI()
+        RI = R.getI()
+    elif VariantM != "KalmanFilterFormula":
+        RI = R.getI()
+    if VariantM == "KalmanFilterFormula":
+        RIdemi = R.sqrtmI()
     #
-    # Point de démarrage de l'optimisation
-    Xini = selfA._parameters["InitializationPoint"]
+    # Initialisation
+    # --------------
+    __n = Xb.size
+    __m = selfA._parameters["NumberOfMembers"]
+    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
+    else:                         Pn = B
+    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
+    else:                         Qn = Q
+    Xn = EnsembleOfBackgroundPerturbations( Xb, None, __m )
+    #~ Xn = EnsembleOfBackgroundPerturbations( Xb, Pn, __m )
     #
-    # Définition de la fonction-coût
-    # ------------------------------
-    def CostFunction(x):
-        _X  = numpy.asmatrix(numpy.ravel( x )).T
-        if selfA._parameters["StoreInternalVariables"] or \
-            selfA._toStore("CurrentState") or \
-            selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentState"].store( _X )
-        _HX = Hm( _X )
-        _HX = numpy.asmatrix(numpy.ravel( _HX )).T
-        _Innovation = Y - _HX
-        if selfA._toStore("SimulatedObservationAtCurrentState") or \
-            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( _HX )
-        if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( _Innovation )
-        #
-        Jb  = float( 0.5 * (_X - Xb).T * BI * (_X - Xb) )
-        Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
-        J   = Jb + Jo
-        #
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
-        selfA.StoredVariables["CostFunctionJb"].store( Jb )
-        selfA.StoredVariables["CostFunctionJo"].store( Jo )
-        selfA.StoredVariables["CostFunctionJ" ].store( J )
-        if selfA._toStore("IndexOfOptimum") or \
-            selfA._toStore("CurrentOptimum") or \
-            selfA._toStore("CostFunctionJAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJoAtCurrentOptimum") or \
-            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-        if selfA._toStore("IndexOfOptimum"):
-            selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
-        if selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
-        if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin] )
-        if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
-        if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
-        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
-        return J
-    #
-    def GradientOfCostFunction(x):
-        _X      = numpy.asmatrix(numpy.ravel( x )).T
-        _HX     = Hm( _X )
-        _HX     = numpy.asmatrix(numpy.ravel( _HX )).T
-        GradJb  = BI * (_X - Xb)
-        GradJo  = - Ha( (_X, RI * (Y - _HX)) )
-        GradJ   = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
-        return GradJ
-    #
-    # Minimisation de la fonctionnelle
-    # --------------------------------
-    nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
-    #
-    if selfA._parameters["Minimizer"] == "LBFGSB":
-        if "0.19" <= scipy.version.version <= "1.1.0":
-            import lbfgsbhlt as optimiseur
-        else:
-            import scipy.optimize as optimiseur
-        Minimum, J_optimal, Informations = optimiseur.fmin_l_bfgs_b(
-            func        = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            bounds      = selfA._parameters["Bounds"],
-            maxfun      = selfA._parameters["MaximumNumberOfSteps"]-1,
-            factr       = selfA._parameters["CostDecrementTolerance"]*1.e14,
-            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
-            iprint      = selfA._parameters["optiprint"],
-            )
-        nfeval = Informations['funcalls']
-        rc     = Informations['warnflag']
-    elif selfA._parameters["Minimizer"] == "TNC":
-        Minimum, nfeval, rc = scipy.optimize.fmin_tnc(
-            func        = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            bounds      = selfA._parameters["Bounds"],
-            maxfun      = selfA._parameters["MaximumNumberOfSteps"],
-            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
-            ftol        = selfA._parameters["CostDecrementTolerance"],
-            messages    = selfA._parameters["optmessages"],
-            )
-    elif selfA._parameters["Minimizer"] == "CG":
-        Minimum, fopt, nfeval, grad_calls, rc = scipy.optimize.fmin_cg(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            gtol        = selfA._parameters["GradientNormTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    elif selfA._parameters["Minimizer"] == "NCG":
-        Minimum, fopt, nfeval, grad_calls, hcalls, rc = scipy.optimize.fmin_ncg(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            avextol     = selfA._parameters["CostDecrementTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    elif selfA._parameters["Minimizer"] == "BFGS":
-        Minimum, fopt, gopt, Hopt, nfeval, grad_calls, rc = scipy.optimize.fmin_bfgs(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            gtol        = selfA._parameters["GradientNormTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    else:
-        raise ValueError("Error in Minimizer name: %s"%selfA._parameters["Minimizer"])
-    #
-    IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-    MinJ     = selfA.StoredVariables["CostFunctionJ"][IndexMin]
-    #
-    # Correction pour pallier a un bug de TNC sur le retour du Minimum
-    # ----------------------------------------------------------------
-    if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
-        Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
-    #
-    # Obtention de l'analyse
-    # ----------------------
-    Xa = numpy.asmatrix(numpy.ravel( Minimum )).T
+    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
+        selfA.StoredVariables["Analysis"].store( Xb )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            covarianceXa = Pn
     #
-    selfA.StoredVariables["Analysis"].store( Xa )
+    previousJMinimum = numpy.finfo(float).max
     #
-    if selfA._toStore("OMA") or \
-        selfA._toStore("SigmaObs2") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("SimulatedObservationAtOptimum"):
-        if selfA._toStore("SimulatedObservationAtCurrentState"):
-            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin]
-        elif selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"][-1]
+    for step in range(duration-1):
+        if hasattr(Y,"store"):
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            HXa = Hm( Xa )
-    #
-    # Calcul de la covariance d'analyse
-    # ---------------------------------
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("JacobianMatrixAtOptimum") or \
-        selfA._toStore("KalmanGainAtOptimum"):
-        HtM = HO["Tangent"].asMatrix(ValueForMethodForm = Xa)
-        HtM = HtM.reshape(Y.size,Xa.size) # ADAO & check shape
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("KalmanGainAtOptimum"):
-        HaM = HO["Adjoint"].asMatrix(ValueForMethodForm = Xa)
-        HaM = HaM.reshape(Xa.size,Y.size) # ADAO & check shape
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles"):
-        HessienneI = []
-        nb = Xa.size
-        for i in range(nb):
-            _ee    = numpy.matrix(numpy.zeros(nb)).T
-            _ee[i] = 1.
-            _HtEE  = numpy.dot(HtM,_ee)
-            _HtEE  = numpy.asmatrix(numpy.ravel( _HtEE )).T
-            HessienneI.append( numpy.ravel( BI*_ee + HaM * (RI * _HtEE) ) )
-        HessienneI = numpy.matrix( HessienneI )
-        A = HessienneI.I
-        if min(A.shape) != max(A.shape):
-            raise ValueError("The %s a posteriori covariance matrix A is of shape %s, despites it has to be a squared matrix. There is an error in the observation operator, please check it."%(selfA._name,str(A.shape)))
-        if (numpy.diag(A) < 0).any():
-            raise ValueError("The %s a posteriori covariance matrix A has at least one negative value on its diagonal. There is an error in the observation operator, please check it."%(selfA._name,))
-        if logging.getLogger().level < logging.WARNING: # La verification n'a lieu qu'en debug
-            try:
-                L = numpy.linalg.cholesky( A )
-            except:
-                raise ValueError("The %s a posteriori covariance matrix A is not symmetric positive-definite. Please check your a priori covariances and your observation operator."%(selfA._name,))
-    if selfA._toStore("APosterioriCovariance"):
-        selfA.StoredVariables["APosterioriCovariance"].store( A )
-    if selfA._toStore("JacobianMatrixAtOptimum"):
-        selfA.StoredVariables["JacobianMatrixAtOptimum"].store( HtM )
-    if selfA._toStore("KalmanGainAtOptimum"):
-        if   (Y.size <= Xb.size): KG  = B * HaM * (R + numpy.dot(HtM, B * HaM)).I
-        elif (Y.size >  Xb.size): KG = (BI + numpy.dot(HaM, RI * HtM)).I * HaM * RI
-        selfA.StoredVariables["KalmanGainAtOptimum"].store( KG )
-    #
-    # Calculs et/ou stockages supplémentaires
-    # ---------------------------------------
-    if selfA._toStore("Innovation") or \
-        selfA._toStore("SigmaObs2") or \
-        selfA._toStore("MahalanobisConsistency") or \
-        selfA._toStore("OMB"):
-        d  = Y - HXb
-    if selfA._toStore("Innovation"):
-        selfA.StoredVariables["Innovation"].store( numpy.ravel(d) )
-    if selfA._toStore("BMA"):
-        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
-    if selfA._toStore("OMA"):
-        selfA.StoredVariables["OMA"].store( numpy.ravel(Y) - numpy.ravel(HXa) )
-    if selfA._toStore("OMB"):
-        selfA.StoredVariables["OMB"].store( numpy.ravel(d) )
-    if selfA._toStore("SigmaObs2"):
-        TraceR = R.trace(Y.size)
-        selfA.StoredVariables["SigmaObs2"].store( float( (d.T * (numpy.asmatrix(numpy.ravel(Y)).T-numpy.asmatrix(numpy.ravel(HXa)).T)) ) / TraceR )
-    if selfA._toStore("MahalanobisConsistency"):
-        selfA.StoredVariables["MahalanobisConsistency"].store( float( 2.*MinJ/d.size ) )
-    if selfA._toStore("SimulationQuantiles"):
-        nech = selfA._parameters["NumberOfSamplesForQuantiles"]
-        HXa  = numpy.matrix(numpy.ravel( HXa )).T
-        YfQ  = None
-        for i in range(nech):
-            if selfA._parameters["SimulationForQuantiles"] == "Linear":
-                dXr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A) - Xa.A1).T
-                dYr = numpy.matrix(numpy.ravel( HtM * dXr )).T
-                Yr = HXa + dYr
-            elif selfA._parameters["SimulationForQuantiles"] == "NonLinear":
-                Xr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A)).T
-                Yr = numpy.matrix(numpy.ravel( Hm( Xr ) )).T
-            if YfQ is None:
-                YfQ = Yr
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
+        #
+        if U is not None:
+            if hasattr(U,"store") and len(U)>1:
+                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
+            elif hasattr(U,"store") and len(U)==1:
+                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
             else:
-                YfQ = numpy.hstack((YfQ,Yr))
-        YfQ.sort(axis=-1)
-        YQ = None
-        for quantile in selfA._parameters["Quantiles"]:
-            if not (0. <= float(quantile) <= 1.): continue
-            indice = int(nech * float(quantile) - 1./nech)
-            if YQ is None: YQ = YfQ[:,indice]
-            else:          YQ = numpy.hstack((YQ,YfQ[:,indice]))
-        selfA.StoredVariables["SimulationQuantiles"].store( YQ )
-    if selfA._toStore("SimulatedObservationAtBackground"):
-        selfA.StoredVariables["SimulatedObservationAtBackground"].store( numpy.ravel(HXb) )
-    if selfA._toStore("SimulatedObservationAtOptimum"):
-        selfA.StoredVariables["SimulatedObservationAtOptimum"].store( numpy.ravel(HXa) )
-    #
-    return 0
-
-# ==============================================================================
-def van3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
-    """
-    3DVAR variational analysis with no inversion of B
-    """
-    #
-    # Initialisations
-    # ---------------
-    #
-    # Opérateurs
-    Hm = HO["Direct"].appliedTo
-    Ha = HO["Adjoint"].appliedInXTo
-    #
-    # Précalcul des inversions de B et R
-    BT = B.getT()
-    RI = R.getI()
-    #
-    # Point de démarrage de l'optimisation
-    Xini = numpy.zeros(Xb.shape)
-    #
-    # Définition de la fonction-coût
-    # ------------------------------
-    def CostFunction(v):
-        _V = numpy.asmatrix(numpy.ravel( v )).T
-        _X = Xb + B * _V
-        if selfA._parameters["StoreInternalVariables"] or \
-            selfA._toStore("CurrentState") or \
-            selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentState"].store( _X )
-        _HX = Hm( _X )
-        _HX = numpy.asmatrix(numpy.ravel( _HX )).T
-        _Innovation = Y - _HX
-        if selfA._toStore("SimulatedObservationAtCurrentState") or \
-            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( _HX )
-        if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( _Innovation )
+                Un = numpy.asmatrix(numpy.ravel( U )).T
+        else:
+            Un = None
         #
-        Jb  = float( 0.5 * _V.T * BT * _V )
-        Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
-        J   = Jb + Jo
+        if selfA._parameters["InflationType"] == "MultiplicativeOnBackgroundAnomalies":
+            Xn = CovarianceInflation( Xn,
+                selfA._parameters["InflationType"],
+                selfA._parameters["InflationFactor"],
+                )
         #
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
-        selfA.StoredVariables["CostFunctionJb"].store( Jb )
-        selfA.StoredVariables["CostFunctionJo"].store( Jo )
-        selfA.StoredVariables["CostFunctionJ" ].store( J )
-        if selfA._toStore("IndexOfOptimum") or \
-            selfA._toStore("CurrentOptimum") or \
-            selfA._toStore("CostFunctionJAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJoAtCurrentOptimum") or \
-            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-        if selfA._toStore("IndexOfOptimum"):
-            selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
-        if selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
-        if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin] )
-        if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
-        if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
-        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
-        return J
-    #
-    def GradientOfCostFunction(v):
-        _V = numpy.asmatrix(numpy.ravel( v )).T
-        _X = Xb + B * _V
-        _HX     = Hm( _X )
-        _HX     = numpy.asmatrix(numpy.ravel( _HX )).T
-        GradJb  = BT * _V
-        GradJo  = - Ha( (_X, RI * (Y - _HX)) )
-        GradJ   = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
-        return GradJ
-    #
-    # Minimisation de la fonctionnelle
-    # --------------------------------
-    nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
-    #
-    if selfA._parameters["Minimizer"] == "LBFGSB":
-        if "0.19" <= scipy.version.version <= "1.1.0":
-            import lbfgsbhlt as optimiseur
+        if selfA._parameters["EstimationOf"] == "State": # Forecast + Q and observation of forecast
+            EMX = M( [(Xn[:,i], Un) for i in range(__m)],
+                argsAsSerie = True,
+                returnSerieAsArrayMatrix = True )
+            qi = numpy.random.multivariate_normal(numpy.zeros(__n), Qn, size=__m).T
+            Xn_predicted = EMX + qi
+            HX_predicted = H( [(Xn_predicted[:,i], Un) for i in range(__m)],
+                argsAsSerie = True,
+                returnSerieAsArrayMatrix = True )
+            if Cm is not None and Un is not None: # Attention : si Cm est aussi dans M, doublon !
+                Cm = Cm.reshape(__n,Un.size) # ADAO & check shape
+                Xn_predicted = Xn_predicted + Cm * Un
+        elif selfA._parameters["EstimationOf"] == "Parameters": # Observation of forecast
+            # --- > Par principe, M = Id, Q = 0
+            Xn_predicted = Xn
+            HX_predicted = H( [(Xn_predicted[:,i], Un) for i in range(__m)],
+                argsAsSerie = True,
+                returnSerieAsArrayMatrix = True )
+        #
+        # Mean of forecast and observation of forecast
+        Xfm  = Xn_predicted.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+        Hfm  = HX_predicted.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
+        #
+        # Anomalies
+        EaX   = EnsembleOfAnomalies( Xn_predicted, Xfm )
+        EaHX  = EnsembleOfAnomalies( HX_predicted, Hfm)
+        #
+        #--------------------------
+        if VariantM == "KalmanFilterFormula":
+            mS    = RIdemi * EaHX / math.sqrt(__m-1)
+            delta = RIdemi * ( Ynpu - Hfm )
+            mT    = numpy.linalg.inv( numpy.identity(__m) + mS.T @ mS )
+            vw    = mT @ mS.T @ delta
+            #
+            Tdemi = numpy.real(scipy.linalg.sqrtm(mT))
+            mU    = numpy.identity(__m)
+            #
+            EaX   = EaX / math.sqrt(__m-1)
+            Xn    = Xfm + EaX @ ( vw.reshape((__m,1)) + math.sqrt(__m-1) * Tdemi @ mU )
+        #--------------------------
+        elif VariantM == "Variational":
+            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
+            def CostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _Jo = 0.5 * _A.T @ (RI * _A)
+                _Jb = 0.5 * (__m-1) * w.T @ w
+                _J  = _Jo + _Jb
+                return float(_J)
+            def GradientOfCostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _GardJo = - EaHX.T @ (RI * _A)
+                _GradJb = (__m-1) * w.reshape((__m,1))
+                _GradJ  = _GardJo + _GradJb
+                return numpy.ravel(_GradJ)
+            vw = scipy.optimize.fmin_cg(
+                f           = CostFunction,
+                x0          = numpy.zeros(__m),
+                fprime      = GradientOfCostFunction,
+                args        = (),
+                disp        = False,
+                )
+            #
+            Hto = EaHX.T @ (RI * EaHX)
+            Htb = (__m-1) * numpy.identity(__m)
+            Hta = Hto + Htb
+            #
+            Pta = numpy.linalg.inv( Hta )
+            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
+            #
+            Xn  = Xfm + EaX @ (vw[:,None] + EWa)
+        #--------------------------
+        elif VariantM == "FiniteSize11": # Jauge Boc2011
+            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
+            def CostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _Jo = 0.5 * _A.T @ (RI * _A)
+                _Jb = 0.5 * __m * math.log(1 + 1/__m + w.T @ w)
+                _J  = _Jo + _Jb
+                return float(_J)
+            def GradientOfCostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _GardJo = - EaHX.T @ (RI * _A)
+                _GradJb = __m * w.reshape((__m,1)) / (1 + 1/__m + w.T @ w)
+                _GradJ  = _GardJo + _GradJb
+                return numpy.ravel(_GradJ)
+            vw = scipy.optimize.fmin_cg(
+                f           = CostFunction,
+                x0          = numpy.zeros(__m),
+                fprime      = GradientOfCostFunction,
+                args        = (),
+                disp        = False,
+                )
+            #
+            Hto = EaHX.T @ (RI * EaHX)
+            Htb = __m * \
+                ( (1 + 1/__m + vw.T @ vw) * numpy.identity(__m) - 2 * vw @ vw.T ) \
+                / (1 + 1/__m + vw.T @ vw)**2
+            Hta = Hto + Htb
+            #
+            Pta = numpy.linalg.inv( Hta )
+            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
+            #
+            Xn  = Xfm + EaX @ (vw.reshape((__m,1)) + EWa)
+        #--------------------------
+        elif VariantM == "FiniteSize15": # Jauge Boc2015
+            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
+            def CostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _Jo = 0.5 * _A.T * RI * _A
+                _Jb = 0.5 * (__m+1) * math.log(1 + 1/__m + w.T @ w)
+                _J  = _Jo + _Jb
+                return float(_J)
+            def GradientOfCostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _GardJo = - EaHX.T @ (RI * _A)
+                _GradJb = (__m+1) * w.reshape((__m,1)) / (1 + 1/__m + w.T @ w)
+                _GradJ  = _GardJo + _GradJb
+                return numpy.ravel(_GradJ)
+            vw = scipy.optimize.fmin_cg(
+                f           = CostFunction,
+                x0          = numpy.zeros(__m),
+                fprime      = GradientOfCostFunction,
+                args        = (),
+                disp        = False,
+                )
+            #
+            Hto = EaHX.T @ (RI * EaHX)
+            Htb = (__m+1) * \
+                ( (1 + 1/__m + vw.T @ vw) * numpy.identity(__m) - 2 * vw @ vw.T ) \
+                / (1 + 1/__m + vw.T @ vw)**2
+            Hta = Hto + Htb
+            #
+            Pta = numpy.linalg.inv( Hta )
+            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
+            #
+            Xn  = Xfm + EaX @ (vw.reshape((__m,1)) + EWa)
+        #--------------------------
+        elif VariantM == "FiniteSize16": # Jauge Boc2016
+            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
+            def CostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _Jo = 0.5 * _A.T @ (RI * _A)
+                _Jb = 0.5 * (__m+1) * math.log(1 + 1/__m + w.T @ w / (__m-1))
+                _J  = _Jo + _Jb
+                return float(_J)
+            def GradientOfCostFunction(w):
+                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
+                _GardJo = - EaHX.T @ (RI * _A)
+                _GradJb = ((__m+1) / (__m-1)) * w.reshape((__m,1)) / (1 + 1/__m + w.T @ w / (__m-1))
+                _GradJ  = _GardJo + _GradJb
+                return numpy.ravel(_GradJ)
+            vw = scipy.optimize.fmin_cg(
+                f           = CostFunction,
+                x0          = numpy.zeros(__m),
+                fprime      = GradientOfCostFunction,
+                args        = (),
+                disp        = False,
+                )
+            #
+            Hto = EaHX.T @ (RI * EaHX)
+            Htb = ((__m+1) / (__m-1)) * \
+                ( (1 + 1/__m + vw.T @ vw / (__m-1)) * numpy.identity(__m) - 2 * vw @ vw.T / (__m-1) ) \
+                / (1 + 1/__m + vw.T @ vw / (__m-1))**2
+            Hta = Hto + Htb
+            #
+            Pta = numpy.linalg.inv( Hta )
+            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
+            #
+            Xn  = Xfm + EaX @ (vw[:,None] + EWa)
+        #--------------------------
         else:
-            import scipy.optimize as optimiseur
-        Minimum, J_optimal, Informations = optimiseur.fmin_l_bfgs_b(
-            func        = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            bounds      = selfA._parameters["Bounds"],
-            maxfun      = selfA._parameters["MaximumNumberOfSteps"]-1,
-            factr       = selfA._parameters["CostDecrementTolerance"]*1.e14,
-            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
-            iprint      = selfA._parameters["optiprint"],
-            )
-        nfeval = Informations['funcalls']
-        rc     = Informations['warnflag']
-    elif selfA._parameters["Minimizer"] == "TNC":
-        Minimum, nfeval, rc = scipy.optimize.fmin_tnc(
-            func        = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            bounds      = selfA._parameters["Bounds"],
-            maxfun      = selfA._parameters["MaximumNumberOfSteps"],
-            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
-            ftol        = selfA._parameters["CostDecrementTolerance"],
-            messages    = selfA._parameters["optmessages"],
-            )
-    elif selfA._parameters["Minimizer"] == "CG":
-        Minimum, fopt, nfeval, grad_calls, rc = scipy.optimize.fmin_cg(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            gtol        = selfA._parameters["GradientNormTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    elif selfA._parameters["Minimizer"] == "NCG":
-        Minimum, fopt, nfeval, grad_calls, hcalls, rc = scipy.optimize.fmin_ncg(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            avextol     = selfA._parameters["CostDecrementTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    elif selfA._parameters["Minimizer"] == "BFGS":
-        Minimum, fopt, gopt, Hopt, nfeval, grad_calls, rc = scipy.optimize.fmin_bfgs(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            gtol        = selfA._parameters["GradientNormTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    else:
-        raise ValueError("Error in Minimizer name: %s"%selfA._parameters["Minimizer"])
+            raise ValueError("VariantM has to be chosen in the authorized methods list.")
+        #
+        if selfA._parameters["InflationType"] == "MultiplicativeOnAnalysisAnomalies":
+            Xn = CovarianceInflation( Xn,
+                selfA._parameters["InflationType"],
+                selfA._parameters["InflationFactor"],
+                )
+        #
+        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+        #--------------------------
+        #
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CostFunctionJ") \
+            or selfA._toStore("CostFunctionJb") \
+            or selfA._toStore("CostFunctionJo") \
+            or selfA._toStore("APosterioriCovariance") \
+            or selfA._toStore("InnovationAtCurrentAnalysis") \
+            or selfA._toStore("SimulatedObservationAtCurrentAnalysis") \
+            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            _HXa = numpy.asmatrix(numpy.ravel( H((Xa, Un)) )).T
+            _Innovation = Ynpu - _HXa
+        #
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        # ---> avec analysis
+        selfA.StoredVariables["Analysis"].store( Xa )
+        if selfA._toStore("SimulatedObservationAtCurrentAnalysis"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"].store( _HXa )
+        if selfA._toStore("InnovationAtCurrentAnalysis"):
+            selfA.StoredVariables["InnovationAtCurrentAnalysis"].store( _Innovation )
+        # ---> avec current state
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CurrentState"):
+            selfA.StoredVariables["CurrentState"].store( Xn )
+        if selfA._toStore("ForecastState"):
+            selfA.StoredVariables["ForecastState"].store( EMX )
+        if selfA._toStore("BMA"):
+            selfA.StoredVariables["BMA"].store( EMX - Xa.reshape((__n,1)) )
+        if selfA._toStore("InnovationAtCurrentState"):
+            selfA.StoredVariables["InnovationAtCurrentState"].store( - HX_predicted + Ynpu )
+        if selfA._toStore("SimulatedObservationAtCurrentState") \
+            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HX_predicted )
+        # ---> autres
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CostFunctionJ") \
+            or selfA._toStore("CostFunctionJb") \
+            or selfA._toStore("CostFunctionJo") \
+            or selfA._toStore("CurrentOptimum") \
+            or selfA._toStore("APosterioriCovariance"):
+            Jb  = float( 0.5 * (Xa - Xb).T * BI * (Xa - Xb) )
+            Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
+            J   = Jb + Jo
+            selfA.StoredVariables["CostFunctionJb"].store( Jb )
+            selfA.StoredVariables["CostFunctionJo"].store( Jo )
+            selfA.StoredVariables["CostFunctionJ" ].store( J )
+            #
+            if selfA._toStore("IndexOfOptimum") \
+                or selfA._toStore("CurrentOptimum") \
+                or selfA._toStore("CostFunctionJAtCurrentOptimum") \
+                or selfA._toStore("CostFunctionJbAtCurrentOptimum") \
+                or selfA._toStore("CostFunctionJoAtCurrentOptimum") \
+                or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+            if selfA._toStore("IndexOfOptimum"):
+                selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
+            if selfA._toStore("CurrentOptimum"):
+                selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["Analysis"][IndexMin] )
+            if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"][IndexMin] )
+            if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
+            if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+            if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
+        if selfA._parameters["EstimationOf"] == "Parameters" \
+            and J < previousJMinimum:
+            previousJMinimum    = J
+            XaMin               = Xa
+            if selfA._toStore("APosterioriCovariance"):
+                covarianceXaMin = Pn
+        # ---> Pour les smoothers
+        if selfA._toStore("CurrentEnsembleState"):
+            selfA.StoredVariables["CurrentEnsembleState"].store( Xn )
     #
-    IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-    MinJ     = selfA.StoredVariables["CostFunctionJ"][IndexMin]
+    # Stockage final supplémentaire de l'optimum en estimation de paramètres
+    # ----------------------------------------------------------------------
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        selfA.StoredVariables["Analysis"].store( XaMin )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( covarianceXaMin )
+        if selfA._toStore("BMA"):
+            selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(XaMin) )
     #
-    # Correction pour pallier a un bug de TNC sur le retour du Minimum
-    # ----------------------------------------------------------------
-    if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
-        Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
-        Minimum = numpy.asmatrix(numpy.ravel( Minimum )).T
-    else:
-        Minimum = Xb + B * numpy.asmatrix(numpy.ravel( Minimum )).T
+    return 0
+
+# ==============================================================================
+def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
+    BnotT=False, _epsilon=1.e-3, _e=1.e-7, _jmax=15000):
+    """
+    Iterative EnKF
+    """
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA._parameters["StoreInternalVariables"] = True
     #
-    # Obtention de l'analyse
-    # ----------------------
-    Xa = Minimum
+    # Opérateurs
+    # ----------
+    H = HO["Direct"].appliedControledFormTo
     #
-    selfA.StoredVariables["Analysis"].store( Xa )
+    if selfA._parameters["EstimationOf"] == "State":
+        M = EM["Direct"].appliedControledFormTo
     #
-    if selfA._toStore("OMA") or \
-        selfA._toStore("SigmaObs2") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("SimulatedObservationAtOptimum"):
-        if selfA._toStore("SimulatedObservationAtCurrentState"):
-            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin]
-        elif selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"][-1]
-        else:
-            HXa = Hm( Xa )
+    if CM is not None and "Tangent" in CM and U is not None:
+        Cm = CM["Tangent"].asMatrix(Xb)
+    else:
+        Cm = None
     #
-    # Calcul de la covariance d'analyse
-    # ---------------------------------
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("JacobianMatrixAtOptimum") or \
-        selfA._toStore("KalmanGainAtOptimum"):
-        HtM = HO["Tangent"].asMatrix(ValueForMethodForm = Xa)
-        HtM = HtM.reshape(Y.size,Xa.size) # ADAO & check shape
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("KalmanGainAtOptimum"):
-        HaM = HO["Adjoint"].asMatrix(ValueForMethodForm = Xa)
-        HaM = HaM.reshape(Xa.size,Y.size) # ADAO & check shape
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles"):
+    # Nombre de pas identique au nombre de pas d'observations
+    # -------------------------------------------------------
+    if hasattr(Y,"stepnumber"):
+        duration = Y.stepnumber()
+        __p = numpy.cumprod(Y.shape())[-1]
+    else:
+        duration = 2
+        __p = numpy.array(Y).size
+    #
+    # Précalcul des inversions de B et R
+    # ----------------------------------
+    if selfA._parameters["StoreInternalVariables"] \
+        or selfA._toStore("CostFunctionJ") \
+        or selfA._toStore("CostFunctionJb") \
+        or selfA._toStore("CostFunctionJo") \
+        or selfA._toStore("CurrentOptimum") \
+        or selfA._toStore("APosterioriCovariance"):
         BI = B.getI()
-        HessienneI = []
-        nb = Xa.size
-        for i in range(nb):
-            _ee    = numpy.matrix(numpy.zeros(nb)).T
-            _ee[i] = 1.
-            _HtEE  = numpy.dot(HtM,_ee)
-            _HtEE  = numpy.asmatrix(numpy.ravel( _HtEE )).T
-            HessienneI.append( numpy.ravel( BI*_ee + HaM * (RI * _HtEE) ) )
-        HessienneI = numpy.matrix( HessienneI )
-        A = HessienneI.I
-        if min(A.shape) != max(A.shape):
-            raise ValueError("The %s a posteriori covariance matrix A is of shape %s, despites it has to be a squared matrix. There is an error in the observation operator, please check it."%(selfA._name,str(A.shape)))
-        if (numpy.diag(A) < 0).any():
-            raise ValueError("The %s a posteriori covariance matrix A has at least one negative value on its diagonal. There is an error in the observation operator, please check it."%(selfA._name,))
-        if logging.getLogger().level < logging.WARNING: # La verification n'a lieu qu'en debug
-            try:
-                L = numpy.linalg.cholesky( A )
-            except:
-                raise ValueError("The %s a posteriori covariance matrix A is not symmetric positive-definite. Please check your a priori covariances and your observation operator."%(selfA._name,))
-    if selfA._toStore("APosterioriCovariance"):
-        selfA.StoredVariables["APosterioriCovariance"].store( A )
-    if selfA._toStore("JacobianMatrixAtOptimum"):
-        selfA.StoredVariables["JacobianMatrixAtOptimum"].store( HtM )
-    if selfA._toStore("KalmanGainAtOptimum"):
-        if   (Y.size <= Xb.size): KG  = B * HaM * (R + numpy.dot(HtM, B * HaM)).I
-        elif (Y.size >  Xb.size): KG = (BI + numpy.dot(HaM, RI * HtM)).I * HaM * RI
-        selfA.StoredVariables["KalmanGainAtOptimum"].store( KG )
+    RI = R.getI()
     #
-    # Calculs et/ou stockages supplémentaires
-    # ---------------------------------------
-    if selfA._toStore("Innovation") or \
-        selfA._toStore("SigmaObs2") or \
-        selfA._toStore("MahalanobisConsistency") or \
-        selfA._toStore("OMB"):
-        d  = Y - HXb
-    if selfA._toStore("Innovation"):
-        selfA.StoredVariables["Innovation"].store( numpy.ravel(d) )
-    if selfA._toStore("BMA"):
-        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
-    if selfA._toStore("OMA"):
-        selfA.StoredVariables["OMA"].store( numpy.ravel(Y) - numpy.ravel(HXa) )
-    if selfA._toStore("OMB"):
-        selfA.StoredVariables["OMB"].store( numpy.ravel(d) )
-    if selfA._toStore("SigmaObs2"):
-        TraceR = R.trace(Y.size)
-        selfA.StoredVariables["SigmaObs2"].store( float( (d.T * (numpy.asmatrix(numpy.ravel(Y)).T-numpy.asmatrix(numpy.ravel(HXa)).T)) ) / TraceR )
-    if selfA._toStore("MahalanobisConsistency"):
-        selfA.StoredVariables["MahalanobisConsistency"].store( float( 2.*MinJ/d.size ) )
-    if selfA._toStore("SimulationQuantiles"):
-        nech = selfA._parameters["NumberOfSamplesForQuantiles"]
-        HXa  = numpy.matrix(numpy.ravel( HXa )).T
-        YfQ  = None
-        for i in range(nech):
-            if selfA._parameters["SimulationForQuantiles"] == "Linear":
-                dXr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A) - Xa.A1).T
-                dYr = numpy.matrix(numpy.ravel( HtM * dXr )).T
-                Yr = HXa + dYr
-            elif selfA._parameters["SimulationForQuantiles"] == "NonLinear":
-                Xr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A)).T
-                Yr = numpy.matrix(numpy.ravel( Hm( Xr ) )).T
-            if YfQ is None:
-                YfQ = Yr
+    # Initialisation
+    # --------------
+    __n = Xb.size
+    __m = selfA._parameters["NumberOfMembers"]
+    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
+    else:                         Pn = B
+    if hasattr(R,"asfullmatrix"): Rn = R.asfullmatrix(__p)
+    else:                         Rn = R
+    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
+    else:                         Qn = Q
+    Xn = EnsembleOfBackgroundPerturbations( Xb, Pn, __m )
+    #
+    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
+        selfA.StoredVariables["Analysis"].store( Xb )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            covarianceXa = Pn
+    #
+    previousJMinimum = numpy.finfo(float).max
+    #
+    for step in range(duration-1):
+        if hasattr(Y,"store"):
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
+        else:
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
+        #
+        if U is not None:
+            if hasattr(U,"store") and len(U)>1:
+                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
+            elif hasattr(U,"store") and len(U)==1:
+                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
             else:
-                YfQ = numpy.hstack((YfQ,Yr))
-        YfQ.sort(axis=-1)
-        YQ = None
-        for quantile in selfA._parameters["Quantiles"]:
-            if not (0. <= float(quantile) <= 1.): continue
-            indice = int(nech * float(quantile) - 1./nech)
-            if YQ is None: YQ = YfQ[:,indice]
-            else:          YQ = numpy.hstack((YQ,YfQ[:,indice]))
-        selfA.StoredVariables["SimulationQuantiles"].store( YQ )
-    if selfA._toStore("SimulatedObservationAtBackground"):
-        selfA.StoredVariables["SimulatedObservationAtBackground"].store( numpy.ravel(HXb) )
-    if selfA._toStore("SimulatedObservationAtOptimum"):
-        selfA.StoredVariables["SimulatedObservationAtOptimum"].store( numpy.ravel(HXa) )
+                Un = numpy.asmatrix(numpy.ravel( U )).T
+        else:
+            Un = None
+        #
+        if selfA._parameters["InflationType"] == "MultiplicativeOnBackgroundAnomalies":
+            Xn = CovarianceInflation( Xn,
+                selfA._parameters["InflationType"],
+                selfA._parameters["InflationFactor"],
+                )
+        #
+        #--------------------------
+        if VariantM == "IEnKF12":
+            Xfm = numpy.ravel(Xn.mean(axis=1, dtype=mfp).astype('float'))
+            EaX = EnsembleOfAnomalies( Xn ) / math.sqrt(__m-1)
+            __j = 0
+            Deltaw = 1
+            if not BnotT:
+                Ta  = numpy.identity(__m)
+            vw  = numpy.zeros(__m)
+            while numpy.linalg.norm(Deltaw) >= _e and __j <= _jmax:
+                vx1 = (Xfm + EaX @ vw).reshape((__n,1))
+                #
+                if BnotT:
+                    E1 = vx1 + _epsilon * EaX
+                else:
+                    E1 = vx1 + math.sqrt(__m-1) * EaX @ Ta
+                #
+                if selfA._parameters["EstimationOf"] == "State": # Forecast + Q
+                    E2 = M( [(E1[:,i,numpy.newaxis], Un) for i in range(__m)],
+                        argsAsSerie = True,
+                        returnSerieAsArrayMatrix = True )
+                elif selfA._parameters["EstimationOf"] == "Parameters":
+                    # --- > Par principe, M = Id
+                    E2 = Xn
+                vx2 = E2.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+                vy1 = H((vx2, Un)).reshape((__p,1))
+                #
+                HE2 = H( [(E2[:,i,numpy.newaxis], Un) for i in range(__m)],
+                    argsAsSerie = True,
+                    returnSerieAsArrayMatrix = True )
+                vy2 = HE2.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
+                #
+                if BnotT:
+                    EaY = (HE2 - vy2) / _epsilon
+                else:
+                    EaY = ( (HE2 - vy2) @ numpy.linalg.inv(Ta) ) / math.sqrt(__m-1)
+                #
+                GradJ = numpy.ravel(vw[:,None] - EaY.transpose() @ (RI * ( Ynpu - vy1 )))
+                mH = numpy.identity(__m) + EaY.transpose() @ (RI * EaY)
+                Deltaw = - numpy.linalg.solve(mH,GradJ)
+                #
+                vw = vw + Deltaw
+                #
+                if not BnotT:
+                    Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
+                #
+                __j = __j + 1
+            #
+            A2 = EnsembleOfAnomalies( E2 )
+            #
+            if BnotT:
+                Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
+                A2 = math.sqrt(__m-1) * A2 @ Ta / _epsilon
+            #
+            Xn = vx2 + A2
+        #--------------------------
+        else:
+            raise ValueError("VariantM has to be chosen in the authorized methods list.")
+        #
+        if selfA._parameters["InflationType"] == "MultiplicativeOnAnalysisAnomalies":
+            Xn = CovarianceInflation( Xn,
+                selfA._parameters["InflationType"],
+                selfA._parameters["InflationFactor"],
+                )
+        #
+        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+        #--------------------------
+        #
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CostFunctionJ") \
+            or selfA._toStore("CostFunctionJb") \
+            or selfA._toStore("CostFunctionJo") \
+            or selfA._toStore("APosterioriCovariance") \
+            or selfA._toStore("InnovationAtCurrentAnalysis") \
+            or selfA._toStore("SimulatedObservationAtCurrentAnalysis") \
+            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            _HXa = numpy.asmatrix(numpy.ravel( H((Xa, Un)) )).T
+            _Innovation = Ynpu - _HXa
+        #
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        # ---> avec analysis
+        selfA.StoredVariables["Analysis"].store( Xa )
+        if selfA._toStore("SimulatedObservationAtCurrentAnalysis"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"].store( _HXa )
+        if selfA._toStore("InnovationAtCurrentAnalysis"):
+            selfA.StoredVariables["InnovationAtCurrentAnalysis"].store( _Innovation )
+        # ---> avec current state
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CurrentState"):
+            selfA.StoredVariables["CurrentState"].store( Xn )
+        if selfA._toStore("ForecastState"):
+            selfA.StoredVariables["ForecastState"].store( E2 )
+        if selfA._toStore("BMA"):
+            selfA.StoredVariables["BMA"].store( E2 - Xa )
+        if selfA._toStore("InnovationAtCurrentState"):
+            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu )
+        if selfA._toStore("SimulatedObservationAtCurrentState") \
+            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
+        # ---> autres
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CostFunctionJ") \
+            or selfA._toStore("CostFunctionJb") \
+            or selfA._toStore("CostFunctionJo") \
+            or selfA._toStore("CurrentOptimum") \
+            or selfA._toStore("APosterioriCovariance"):
+            Jb  = float( 0.5 * (Xa - Xb).T * BI * (Xa - Xb) )
+            Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
+            J   = Jb + Jo
+            selfA.StoredVariables["CostFunctionJb"].store( Jb )
+            selfA.StoredVariables["CostFunctionJo"].store( Jo )
+            selfA.StoredVariables["CostFunctionJ" ].store( J )
+            #
+            if selfA._toStore("IndexOfOptimum") \
+                or selfA._toStore("CurrentOptimum") \
+                or selfA._toStore("CostFunctionJAtCurrentOptimum") \
+                or selfA._toStore("CostFunctionJbAtCurrentOptimum") \
+                or selfA._toStore("CostFunctionJoAtCurrentOptimum") \
+                or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+            if selfA._toStore("IndexOfOptimum"):
+                selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
+            if selfA._toStore("CurrentOptimum"):
+                selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["Analysis"][IndexMin] )
+            if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"][IndexMin] )
+            if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
+            if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+            if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
+        if selfA._parameters["EstimationOf"] == "Parameters" \
+            and J < previousJMinimum:
+            previousJMinimum    = J
+            XaMin               = Xa
+            if selfA._toStore("APosterioriCovariance"):
+                covarianceXaMin = Pn
+    #
+    # Stockage final supplémentaire de l'optimum en estimation de paramètres
+    # ----------------------------------------------------------------------
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        selfA.StoredVariables["Analysis"].store( XaMin )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( covarianceXaMin )
+        if selfA._toStore("BMA"):
+            selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(XaMin) )
     #
     return 0
 
@@ -1556,385 +1613,422 @@ def incr3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
     return 0
 
 # ==============================================================================
-def psas3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
+    BnotT=False, _epsilon=1.e-3, _e=1.e-7, _jmax=15000):
     """
-    3DVAR PSAS
+    Maximum Likelihood Ensemble Filter
     """
-    #
-    # Initialisations
-    # ---------------
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA._parameters["StoreInternalVariables"] = True
     #
     # Opérateurs
-    Hm = HO["Direct"].appliedTo
+    # ----------
+    H = HO["Direct"].appliedControledFormTo
     #
-    # Utilisation éventuelle d'un vecteur H(Xb) précalculé
-    if HO["AppliedInX"] is not None and "HXb" in HO["AppliedInX"]:
-        HXb = Hm( Xb, HO["AppliedInX"]["HXb"] )
+    if selfA._parameters["EstimationOf"] == "State":
+        M = EM["Direct"].appliedControledFormTo
+    #
+    if CM is not None and "Tangent" in CM and U is not None:
+        Cm = CM["Tangent"].asMatrix(Xb)
     else:
-        HXb = Hm( Xb )
-    HXb = numpy.asmatrix(numpy.ravel( HXb )).T
-    if Y.size != HXb.size:
-        raise ValueError("The size %i of observations Y and %i of observed calculation H(X) are different, they have to be identical."%(Y.size,HXb.size))
-    if max(Y.shape) != max(HXb.shape):
-        raise ValueError("The shapes %s of observations Y and %s of observed calculation H(X) are different, they have to be identical."%(Y.shape,HXb.shape))
-    #
-    if selfA._toStore("JacobianMatrixAtBackground"):
-        HtMb = HO["Tangent"].asMatrix(ValueForMethodForm = Xb)
-        HtMb = HtMb.reshape(Y.size,Xb.size) # ADAO & check shape
-        selfA.StoredVariables["JacobianMatrixAtBackground"].store( HtMb )
-    #
-    Ht = HO["Tangent"].asMatrix(Xb)
-    BHT = B * Ht.T
-    HBHTpR = R + Ht * BHT
-    Innovation = Y - HXb
-    #
-    # Point de démarrage de l'optimisation
-    Xini = numpy.zeros(Xb.shape)
-    #
-    # Définition de la fonction-coût
-    # ------------------------------
-    def CostFunction(w):
-        _W = numpy.asmatrix(numpy.ravel( w )).T
-        if selfA._parameters["StoreInternalVariables"] or \
-            selfA._toStore("CurrentState") or \
-            selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentState"].store( Xb + BHT * _W )
-        if selfA._toStore("SimulatedObservationAtCurrentState") or \
-            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( Hm( Xb + BHT * _W ) )
-        if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( Innovation )
-        #
-        Jb  = float( 0.5 * _W.T * HBHTpR * _W )
-        Jo  = float( - _W.T * Innovation )
-        J   = Jb + Jo
-        #
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
-        selfA.StoredVariables["CostFunctionJb"].store( Jb )
-        selfA.StoredVariables["CostFunctionJo"].store( Jo )
-        selfA.StoredVariables["CostFunctionJ" ].store( J )
-        if selfA._toStore("IndexOfOptimum") or \
-            selfA._toStore("CurrentOptimum") or \
-            selfA._toStore("CostFunctionJAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJoAtCurrentOptimum") or \
-            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-        if selfA._toStore("IndexOfOptimum"):
-            selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
-        if selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
-        if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin] )
-        if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
-        if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
-        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
-        return J
-    #
-    def GradientOfCostFunction(w):
-        _W = numpy.asmatrix(numpy.ravel( w )).T
-        GradJb  = HBHTpR * _W
-        GradJo  = - Innovation
-        GradJ   = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
-        return GradJ
-    #
-    # Minimisation de la fonctionnelle
-    # --------------------------------
-    nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
+        Cm = None
     #
-    if selfA._parameters["Minimizer"] == "LBFGSB":
-        if "0.19" <= scipy.version.version <= "1.1.0":
-            import lbfgsbhlt as optimiseur
-        else:
-            import scipy.optimize as optimiseur
-        Minimum, J_optimal, Informations = optimiseur.fmin_l_bfgs_b(
-            func        = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            bounds      = selfA._parameters["Bounds"],
-            maxfun      = selfA._parameters["MaximumNumberOfSteps"]-1,
-            factr       = selfA._parameters["CostDecrementTolerance"]*1.e14,
-            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
-            iprint      = selfA._parameters["optiprint"],
-            )
-        nfeval = Informations['funcalls']
-        rc     = Informations['warnflag']
-    elif selfA._parameters["Minimizer"] == "TNC":
-        Minimum, nfeval, rc = scipy.optimize.fmin_tnc(
-            func        = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            bounds      = selfA._parameters["Bounds"],
-            maxfun      = selfA._parameters["MaximumNumberOfSteps"],
-            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
-            ftol        = selfA._parameters["CostDecrementTolerance"],
-            messages    = selfA._parameters["optmessages"],
-            )
-    elif selfA._parameters["Minimizer"] == "CG":
-        Minimum, fopt, nfeval, grad_calls, rc = scipy.optimize.fmin_cg(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            gtol        = selfA._parameters["GradientNormTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    elif selfA._parameters["Minimizer"] == "NCG":
-        Minimum, fopt, nfeval, grad_calls, hcalls, rc = scipy.optimize.fmin_ncg(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            avextol     = selfA._parameters["CostDecrementTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
-    elif selfA._parameters["Minimizer"] == "BFGS":
-        Minimum, fopt, gopt, Hopt, nfeval, grad_calls, rc = scipy.optimize.fmin_bfgs(
-            f           = CostFunction,
-            x0          = Xini,
-            fprime      = GradientOfCostFunction,
-            args        = (),
-            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
-            gtol        = selfA._parameters["GradientNormTolerance"],
-            disp        = selfA._parameters["optdisp"],
-            full_output = True,
-            )
+    # Nombre de pas identique au nombre de pas d'observations
+    # -------------------------------------------------------
+    if hasattr(Y,"stepnumber"):
+        duration = Y.stepnumber()
+        __p = numpy.cumprod(Y.shape())[-1]
     else:
-        raise ValueError("Error in Minimizer name: %s"%selfA._parameters["Minimizer"])
+        duration = 2
+        __p = numpy.array(Y).size
     #
-    IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-    MinJ     = selfA.StoredVariables["CostFunctionJ"][IndexMin]
+    # Précalcul des inversions de B et R
+    # ----------------------------------
+    if selfA._parameters["StoreInternalVariables"] \
+        or selfA._toStore("CostFunctionJ") \
+        or selfA._toStore("CostFunctionJb") \
+        or selfA._toStore("CostFunctionJo") \
+        or selfA._toStore("CurrentOptimum") \
+        or selfA._toStore("APosterioriCovariance"):
+        BI = B.getI()
+    RI = R.getI()
     #
-    # Correction pour pallier a un bug de TNC sur le retour du Minimum
-    # ----------------------------------------------------------------
-    if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
-        Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
-        Minimum = numpy.asmatrix(numpy.ravel( Minimum )).T
-    else:
-        Minimum = Xb + BHT * numpy.asmatrix(numpy.ravel( Minimum )).T
+    # Initialisation
+    # --------------
+    __n = Xb.size
+    __m = selfA._parameters["NumberOfMembers"]
+    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
+    else:                         Pn = B
+    if hasattr(R,"asfullmatrix"): Rn = R.asfullmatrix(__p)
+    else:                         Rn = R
+    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
+    else:                         Qn = Q
+    Xn = EnsembleOfBackgroundPerturbations( Xb, None, __m )
     #
-    # Obtention de l'analyse
-    # ----------------------
-    Xa = Minimum
+    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
+        selfA.StoredVariables["Analysis"].store( Xb )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            covarianceXa = Pn
     #
-    selfA.StoredVariables["Analysis"].store( Xa )
+    previousJMinimum = numpy.finfo(float).max
     #
-    if selfA._toStore("OMA") or \
-        selfA._toStore("SigmaObs2") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("SimulatedObservationAtOptimum"):
-        if selfA._toStore("SimulatedObservationAtCurrentState"):
-            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin]
-        elif selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"][-1]
+    for step in range(duration-1):
+        if hasattr(Y,"store"):
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            HXa = Hm( Xa )
-    #
-    # Calcul de la covariance d'analyse
-    # ---------------------------------
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("JacobianMatrixAtOptimum") or \
-        selfA._toStore("KalmanGainAtOptimum"):
-        HtM = HO["Tangent"].asMatrix(ValueForMethodForm = Xa)
-        HtM = HtM.reshape(Y.size,Xa.size) # ADAO & check shape
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles") or \
-        selfA._toStore("KalmanGainAtOptimum"):
-        HaM = HO["Adjoint"].asMatrix(ValueForMethodForm = Xa)
-        HaM = HaM.reshape(Xa.size,Y.size) # ADAO & check shape
-    if selfA._toStore("APosterioriCovariance") or \
-        selfA._toStore("SimulationQuantiles"):
-        BI = B.getI()
-        RI = R.getI()
-        HessienneI = []
-        nb = Xa.size
-        for i in range(nb):
-            _ee    = numpy.matrix(numpy.zeros(nb)).T
-            _ee[i] = 1.
-            _HtEE  = numpy.dot(HtM,_ee)
-            _HtEE  = numpy.asmatrix(numpy.ravel( _HtEE )).T
-            HessienneI.append( numpy.ravel( BI*_ee + HaM * (RI * _HtEE) ) )
-        HessienneI = numpy.matrix( HessienneI )
-        A = HessienneI.I
-        if min(A.shape) != max(A.shape):
-            raise ValueError("The %s a posteriori covariance matrix A is of shape %s, despites it has to be a squared matrix. There is an error in the observation operator, please check it."%(selfA._name,str(A.shape)))
-        if (numpy.diag(A) < 0).any():
-            raise ValueError("The %s a posteriori covariance matrix A has at least one negative value on its diagonal. There is an error in the observation operator, please check it."%(selfA._name,))
-        if logging.getLogger().level < logging.WARNING: # La verification n'a lieu qu'en debug
-            try:
-                L = numpy.linalg.cholesky( A )
-            except:
-                raise ValueError("The %s a posteriori covariance matrix A is not symmetric positive-definite. Please check your a priori covariances and your observation operator."%(selfA._name,))
-    if selfA._toStore("APosterioriCovariance"):
-        selfA.StoredVariables["APosterioriCovariance"].store( A )
-    if selfA._toStore("JacobianMatrixAtOptimum"):
-        selfA.StoredVariables["JacobianMatrixAtOptimum"].store( HtM )
-    if selfA._toStore("KalmanGainAtOptimum"):
-        if   (Y.size <= Xb.size): KG  = B * HaM * (R + numpy.dot(HtM, B * HaM)).I
-        elif (Y.size >  Xb.size): KG = (BI + numpy.dot(HaM, RI * HtM)).I * HaM * RI
-        selfA.StoredVariables["KalmanGainAtOptimum"].store( KG )
-    #
-    # Calculs et/ou stockages supplémentaires
-    # ---------------------------------------
-    if selfA._toStore("Innovation") or \
-        selfA._toStore("SigmaObs2") or \
-        selfA._toStore("MahalanobisConsistency") or \
-        selfA._toStore("OMB"):
-        d  = Y - HXb
-    if selfA._toStore("Innovation"):
-        selfA.StoredVariables["Innovation"].store( numpy.ravel(d) )
-    if selfA._toStore("BMA"):
-        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
-    if selfA._toStore("OMA"):
-        selfA.StoredVariables["OMA"].store( numpy.ravel(Y) - numpy.ravel(HXa) )
-    if selfA._toStore("OMB"):
-        selfA.StoredVariables["OMB"].store( numpy.ravel(d) )
-    if selfA._toStore("SigmaObs2"):
-        TraceR = R.trace(Y.size)
-        selfA.StoredVariables["SigmaObs2"].store( float( (d.T * (numpy.asmatrix(numpy.ravel(Y)).T-numpy.asmatrix(numpy.ravel(HXa)).T)) ) / TraceR )
-    if selfA._toStore("MahalanobisConsistency"):
-        selfA.StoredVariables["MahalanobisConsistency"].store( float( 2.*MinJ/d.size ) )
-    if selfA._toStore("SimulationQuantiles"):
-        nech = selfA._parameters["NumberOfSamplesForQuantiles"]
-        HXa  = numpy.matrix(numpy.ravel( HXa )).T
-        YfQ  = None
-        for i in range(nech):
-            if selfA._parameters["SimulationForQuantiles"] == "Linear":
-                dXr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A) - Xa.A1).T
-                dYr = numpy.matrix(numpy.ravel( HtM * dXr )).T
-                Yr = HXa + dYr
-            elif selfA._parameters["SimulationForQuantiles"] == "NonLinear":
-                Xr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A)).T
-                Yr = numpy.matrix(numpy.ravel( Hm( Xr ) )).T
-            if YfQ is None:
-                YfQ = Yr
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
+        #
+        if U is not None:
+            if hasattr(U,"store") and len(U)>1:
+                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
+            elif hasattr(U,"store") and len(U)==1:
+                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
             else:
-                YfQ = numpy.hstack((YfQ,Yr))
-        YfQ.sort(axis=-1)
-        YQ = None
-        for quantile in selfA._parameters["Quantiles"]:
-            if not (0. <= float(quantile) <= 1.): continue
-            indice = int(nech * float(quantile) - 1./nech)
-            if YQ is None: YQ = YfQ[:,indice]
-            else:          YQ = numpy.hstack((YQ,YfQ[:,indice]))
-        selfA.StoredVariables["SimulationQuantiles"].store( YQ )
-    if selfA._toStore("SimulatedObservationAtBackground"):
-        selfA.StoredVariables["SimulatedObservationAtBackground"].store( numpy.ravel(HXb) )
-    if selfA._toStore("SimulatedObservationAtOptimum"):
-        selfA.StoredVariables["SimulatedObservationAtOptimum"].store( numpy.ravel(HXa) )
+                Un = numpy.asmatrix(numpy.ravel( U )).T
+        else:
+            Un = None
+        #
+        if selfA._parameters["InflationType"] == "MultiplicativeOnBackgroundAnomalies":
+            Xn = CovarianceInflation( Xn,
+                selfA._parameters["InflationType"],
+                selfA._parameters["InflationFactor"],
+                )
+        #
+        if selfA._parameters["EstimationOf"] == "State": # Forecast + Q and observation of forecast
+            EMX = M( [(Xn[:,i], Un) for i in range(__m)],
+                argsAsSerie = True,
+                returnSerieAsArrayMatrix = True )
+            qi = numpy.random.multivariate_normal(numpy.zeros(__n), Qn, size=__m).T
+            Xn_predicted = EMX + qi
+            if Cm is not None and Un is not None: # Attention : si Cm est aussi dans M, doublon !
+                Cm = Cm.reshape(__n,Un.size) # ADAO & check shape
+                Xn_predicted = Xn_predicted + Cm * Un
+        elif selfA._parameters["EstimationOf"] == "Parameters": # Observation of forecast
+            # --- > Par principe, M = Id, Q = 0
+            Xn_predicted = Xn
+        #
+        #--------------------------
+        if VariantM == "MLEF13":
+            Xfm = numpy.ravel(Xn_predicted.mean(axis=1, dtype=mfp).astype('float'))
+            EaX = EnsembleOfAnomalies( Xn_predicted, Xfm, 1./math.sqrt(__m-1) )
+            Ua  = numpy.identity(__m)
+            __j = 0
+            Deltaw = 1
+            if not BnotT:
+                Ta  = numpy.identity(__m)
+            vw  = numpy.zeros(__m)
+            while numpy.linalg.norm(Deltaw) >= _e and __j <= _jmax:
+                vx1 = (Xfm + EaX @ vw).reshape((__n,1))
+                #
+                if BnotT:
+                    E1 = vx1 + _epsilon * EaX
+                else:
+                    E1 = vx1 + math.sqrt(__m-1) * EaX @ Ta
+                #
+                HE2 = H( [(E1[:,i,numpy.newaxis], Un) for i in range(__m)],
+                    argsAsSerie = True,
+                    returnSerieAsArrayMatrix = True )
+                vy2 = HE2.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
+                #
+                if BnotT:
+                    EaY = (HE2 - vy2) / _epsilon
+                else:
+                    EaY = ( (HE2 - vy2) @ numpy.linalg.inv(Ta) ) / math.sqrt(__m-1)
+                #
+                GradJ = numpy.ravel(vw[:,None] - EaY.transpose() @ (RI * ( Ynpu - vy2 )))
+                mH = numpy.identity(__m) + EaY.transpose() @ (RI * EaY)
+                Deltaw = - numpy.linalg.solve(mH,GradJ)
+                #
+                vw = vw + Deltaw
+                #
+                if not BnotT:
+                    Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
+                #
+                __j = __j + 1
+            #
+            if BnotT:
+                Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
+            #
+            Xn = vx1 + math.sqrt(__m-1) * EaX @ Ta @ Ua
+        #--------------------------
+        else:
+            raise ValueError("VariantM has to be chosen in the authorized methods list.")
+        #
+        if selfA._parameters["InflationType"] == "MultiplicativeOnAnalysisAnomalies":
+            Xn = CovarianceInflation( Xn,
+                selfA._parameters["InflationType"],
+                selfA._parameters["InflationFactor"],
+                )
+        #
+        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
+        #--------------------------
+        #
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CostFunctionJ") \
+            or selfA._toStore("CostFunctionJb") \
+            or selfA._toStore("CostFunctionJo") \
+            or selfA._toStore("APosterioriCovariance") \
+            or selfA._toStore("InnovationAtCurrentAnalysis") \
+            or selfA._toStore("SimulatedObservationAtCurrentAnalysis") \
+            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            _HXa = numpy.asmatrix(numpy.ravel( H((Xa, Un)) )).T
+            _Innovation = Ynpu - _HXa
+        #
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        # ---> avec analysis
+        selfA.StoredVariables["Analysis"].store( Xa )
+        if selfA._toStore("SimulatedObservationAtCurrentAnalysis"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"].store( _HXa )
+        if selfA._toStore("InnovationAtCurrentAnalysis"):
+            selfA.StoredVariables["InnovationAtCurrentAnalysis"].store( _Innovation )
+        # ---> avec current state
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CurrentState"):
+            selfA.StoredVariables["CurrentState"].store( Xn )
+        if selfA._toStore("ForecastState"):
+            selfA.StoredVariables["ForecastState"].store( EMX )
+        if selfA._toStore("BMA"):
+            selfA.StoredVariables["BMA"].store( EMX - Xa )
+        if selfA._toStore("InnovationAtCurrentState"):
+            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu )
+        if selfA._toStore("SimulatedObservationAtCurrentState") \
+            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
+        # ---> autres
+        if selfA._parameters["StoreInternalVariables"] \
+            or selfA._toStore("CostFunctionJ") \
+            or selfA._toStore("CostFunctionJb") \
+            or selfA._toStore("CostFunctionJo") \
+            or selfA._toStore("CurrentOptimum") \
+            or selfA._toStore("APosterioriCovariance"):
+            Jb  = float( 0.5 * (Xa - Xb).T * BI * (Xa - Xb) )
+            Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
+            J   = Jb + Jo
+            selfA.StoredVariables["CostFunctionJb"].store( Jb )
+            selfA.StoredVariables["CostFunctionJo"].store( Jo )
+            selfA.StoredVariables["CostFunctionJ" ].store( J )
+            #
+            if selfA._toStore("IndexOfOptimum") \
+                or selfA._toStore("CurrentOptimum") \
+                or selfA._toStore("CostFunctionJAtCurrentOptimum") \
+                or selfA._toStore("CostFunctionJbAtCurrentOptimum") \
+                or selfA._toStore("CostFunctionJoAtCurrentOptimum") \
+                or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+            if selfA._toStore("IndexOfOptimum"):
+                selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
+            if selfA._toStore("CurrentOptimum"):
+                selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["Analysis"][IndexMin] )
+            if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"][IndexMin] )
+            if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
+            if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+            if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+                selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
+        if selfA._parameters["EstimationOf"] == "Parameters" \
+            and J < previousJMinimum:
+            previousJMinimum    = J
+            XaMin               = Xa
+            if selfA._toStore("APosterioriCovariance"):
+                covarianceXaMin = Pn
+    #
+    # Stockage final supplémentaire de l'optimum en estimation de paramètres
+    # ----------------------------------------------------------------------
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
+        selfA.StoredVariables["Analysis"].store( XaMin )
+        if selfA._toStore("APosterioriCovariance"):
+            selfA.StoredVariables["APosterioriCovariance"].store( covarianceXaMin )
+        if selfA._toStore("BMA"):
+            selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(XaMin) )
     #
     return 0
 
 # ==============================================================================
-def std4dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+def mmqr(
+        func     = None,
+        x0       = None,
+        fprime   = None,
+        bounds   = None,
+        quantile = 0.5,
+        maxfun   = 15000,
+        toler    = 1.e-06,
+        y        = None,
+        ):
     """
-    4DVAR
+    Implémentation informatique de l'algorithme MMQR, basée sur la publication :
+    David R. Hunter, Kenneth Lange, "Quantile Regression via an MM Algorithm",
+    Journal of Computational and Graphical Statistics, 9, 1, pp.60-77, 2000.
     """
     #
-    # Initialisations
-    # ---------------
+    # Recuperation des donnees et informations initiales
+    # --------------------------------------------------
+    variables = numpy.ravel( x0 )
+    mesures   = numpy.ravel( y )
+    increment = sys.float_info[0]
+    p         = variables.size
+    n         = mesures.size
+    quantile  = float(quantile)
     #
-    # Opérateurs
-    Hm = HO["Direct"].appliedControledFormTo
-    Mm = EM["Direct"].appliedControledFormTo
+    # Calcul des parametres du MM
+    # ---------------------------
+    tn      = float(toler) / n
+    e0      = -tn / math.log(tn)
+    epsilon = (e0-tn)/(1+math.log(e0))
     #
-    if CM is not None and "Tangent" in CM and U is not None:
-        Cm = CM["Tangent"].asMatrix(Xb)
-    else:
-        Cm = None
+    # Calculs d'initialisation
+    # ------------------------
+    residus  = mesures - numpy.ravel( func( variables ) )
+    poids    = 1./(epsilon+numpy.abs(residus))
+    veps     = 1. - 2. * quantile - residus * poids
+    lastsurrogate = -numpy.sum(residus*veps) - (1.-2.*quantile)*numpy.sum(residus)
+    iteration = 0
     #
-    def Un(_step):
-        if U is not None:
-            if hasattr(U,"store") and 1<=_step<len(U) :
-                _Un = numpy.asmatrix(numpy.ravel( U[_step] )).T
-            elif hasattr(U,"store") and len(U)==1:
-                _Un = numpy.asmatrix(numpy.ravel( U[0] )).T
-            else:
-                _Un = numpy.asmatrix(numpy.ravel( U )).T
-        else:
-            _Un = None
-        return _Un
-    def CmUn(_xn,_un):
-        if Cm is not None and _un is not None: # Attention : si Cm est aussi dans M, doublon !
-            _Cm   = Cm.reshape(_xn.size,_un.size) # ADAO & check shape
-            _CmUn = _Cm * _un
-        else:
-            _CmUn = 0.
-        return _CmUn
+    # Recherche iterative
+    # -------------------
+    while (increment > toler) and (iteration < maxfun) :
+        iteration += 1
+        #
+        Derivees  = numpy.array(fprime(variables))
+        Derivees  = Derivees.reshape(n,p) # Necessaire pour remettre en place la matrice si elle passe par des tuyaux YACS
+        DeriveesT = Derivees.transpose()
+        M         =   numpy.dot( DeriveesT , (numpy.array(numpy.matrix(p*[poids,]).T)*Derivees) )
+        SM        =   numpy.transpose(numpy.dot( DeriveesT , veps ))
+        step      = - numpy.linalg.lstsq( M, SM, rcond=-1 )[0]
+        #
+        variables = variables + step
+        if bounds is not None:
+            # Attention : boucle infinie à éviter si un intervalle est trop petit
+            while( (variables < numpy.ravel(numpy.asmatrix(bounds)[:,0])).any() or (variables > numpy.ravel(numpy.asmatrix(bounds)[:,1])).any() ):
+                step      = step/2.
+                variables = variables - step
+        residus   = mesures - numpy.ravel( func(variables) )
+        surrogate = numpy.sum(residus**2 * poids) + (4.*quantile-2.) * numpy.sum(residus)
+        #
+        while ( (surrogate > lastsurrogate) and ( max(list(numpy.abs(step))) > 1.e-16 ) ) :
+            step      = step/2.
+            variables = variables - step
+            residus   = mesures - numpy.ravel( func(variables) )
+            surrogate = numpy.sum(residus**2 * poids) + (4.*quantile-2.) * numpy.sum(residus)
+        #
+        increment     = lastsurrogate-surrogate
+        poids         = 1./(epsilon+numpy.abs(residus))
+        veps          = 1. - 2. * quantile - residus * poids
+        lastsurrogate = -numpy.sum(residus * veps) - (1.-2.*quantile)*numpy.sum(residus)
     #
-    # Remarque : les observations sont exploitées à partir du pas de temps
-    # numéro 1, et sont utilisées dans Yo comme rangées selon ces indices.
-    # Donc le pas 0 n'est pas utilisé puisque la première étape commence
-    # avec l'observation du pas 1.
+    # Mesure d'écart
+    # --------------
+    Ecart = quantile * numpy.sum(residus) - numpy.sum( residus[residus<0] )
+    #
+    return variables, Ecart, [n,p,iteration,increment,0]
+
+# ==============================================================================
+def multi3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, oneCycle):
+    """
+    3DVAR multi-pas et multi-méthodes
+    """
+    #
+    # Initialisation
+    # --------------
+    Xn = numpy.ravel(Xb).reshape((-1,1))
+    #
+    if selfA._parameters["EstimationOf"] == "State":
+        M = EM["Direct"].appliedTo
+        #
+        if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
+            selfA.StoredVariables["Analysis"].store( Xn )
+            if selfA._toStore("APosterioriCovariance"):
+                if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(Xn.size)
+                else:                         Pn = B
+                selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            if selfA._toStore("ForecastState"):
+                selfA.StoredVariables["ForecastState"].store( Xn )
     #
-    # Nombre de pas identique au nombre de pas d'observations
     if hasattr(Y,"stepnumber"):
         duration = Y.stepnumber()
     else:
         duration = 2
     #
-    # Précalcul des inversions de B et R
-    BI = B.getI()
-    RI = R.getI()
+    # Multi-pas
+    # ---------
+    for step in range(duration-1):
+        if hasattr(Y,"store"):
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((-1,1))
+        else:
+            Ynpu = numpy.ravel( Y ).reshape((-1,1))
+        #
+        if selfA._parameters["EstimationOf"] == "State": # Forecast
+            Xn = selfA.StoredVariables["Analysis"][-1]
+            Xn_predicted = M( Xn )
+            if selfA._toStore("ForecastState"):
+                selfA.StoredVariables["ForecastState"].store( Xn_predicted )
+        elif selfA._parameters["EstimationOf"] == "Parameters": # No forecast
+            # --- > Par principe, M = Id, Q = 0
+            Xn_predicted = Xn
+        Xn_predicted = numpy.ravel(Xn_predicted).reshape((-1,1))
+        #
+        oneCycle(selfA, Xn_predicted, Ynpu, U, HO, None, None, R, B, None)
+    #
+    return 0
+
+# ==============================================================================
+def psas3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+    """
+    3DVAR PSAS
+    """
+    #
+    # Initialisations
+    # ---------------
+    #
+    # Opérateurs
+    Hm = HO["Direct"].appliedTo
+    #
+    # Utilisation éventuelle d'un vecteur H(Xb) précalculé
+    if HO["AppliedInX"] is not None and "HXb" in HO["AppliedInX"]:
+        HXb = Hm( Xb, HO["AppliedInX"]["HXb"] )
+    else:
+        HXb = Hm( Xb )
+    HXb = numpy.asmatrix(numpy.ravel( HXb )).T
+    if Y.size != HXb.size:
+        raise ValueError("The size %i of observations Y and %i of observed calculation H(X) are different, they have to be identical."%(Y.size,HXb.size))
+    if max(Y.shape) != max(HXb.shape):
+        raise ValueError("The shapes %s of observations Y and %s of observed calculation H(X) are different, they have to be identical."%(Y.shape,HXb.shape))
+    #
+    if selfA._toStore("JacobianMatrixAtBackground"):
+        HtMb = HO["Tangent"].asMatrix(ValueForMethodForm = Xb)
+        HtMb = HtMb.reshape(Y.size,Xb.size) # ADAO & check shape
+        selfA.StoredVariables["JacobianMatrixAtBackground"].store( HtMb )
+    #
+    Ht = HO["Tangent"].asMatrix(Xb)
+    BHT = B * Ht.T
+    HBHTpR = R + Ht * BHT
+    Innovation = Y - HXb
     #
     # Point de démarrage de l'optimisation
-    Xini = selfA._parameters["InitializationPoint"]
+    Xini = numpy.zeros(Xb.shape)
     #
     # Définition de la fonction-coût
     # ------------------------------
-    selfA.DirectCalculation = [None,] # Le pas 0 n'est pas observé
-    selfA.DirectInnovation  = [None,] # Le pas 0 n'est pas observé
-    def CostFunction(x):
-        _X  = numpy.asmatrix(numpy.ravel( x )).T
+    def CostFunction(w):
+        _W = numpy.asmatrix(numpy.ravel( w )).T
         if selfA._parameters["StoreInternalVariables"] or \
             selfA._toStore("CurrentState") or \
             selfA._toStore("CurrentOptimum"):
-            selfA.StoredVariables["CurrentState"].store( _X )
-        Jb  = float( 0.5 * (_X - Xb).T * BI * (_X - Xb) )
-        selfA.DirectCalculation = [None,]
-        selfA.DirectInnovation  = [None,]
-        Jo  = 0.
-        _Xn = _X
-        for step in range(0,duration-1):
-            if hasattr(Y,"store"):
-                _Ynpu = numpy.asmatrix(numpy.ravel( Y[step+1] )).T
-            else:
-                _Ynpu = numpy.asmatrix(numpy.ravel( Y )).T
-            _Un = Un(step)
-            #
-            # Etape d'évolution
-            if selfA._parameters["EstimationOf"] == "State":
-                _Xn = Mm( (_Xn, _Un) ) + CmUn(_Xn, _Un)
-            elif selfA._parameters["EstimationOf"] == "Parameters":
-                pass
-            #
-            if selfA._parameters["Bounds"] is not None and selfA._parameters["ConstrainedBy"] == "EstimateProjection":
-                _Xn = numpy.max(numpy.hstack((_Xn,numpy.asmatrix(selfA._parameters["Bounds"])[:,0])),axis=1)
-                _Xn = numpy.min(numpy.hstack((_Xn,numpy.asmatrix(selfA._parameters["Bounds"])[:,1])),axis=1)
-            #
-            # Etape de différence aux observations
-            if selfA._parameters["EstimationOf"] == "State":
-                _YmHMX = _Ynpu - numpy.asmatrix(numpy.ravel( Hm( (_Xn, None) ) )).T
-            elif selfA._parameters["EstimationOf"] == "Parameters":
-                _YmHMX = _Ynpu - numpy.asmatrix(numpy.ravel( Hm( (_Xn, _Un) ) )).T - CmUn(_Xn, _Un)
-            #
-            # Stockage de l'état
-            selfA.DirectCalculation.append( _Xn )
-            selfA.DirectInnovation.append( _YmHMX )
-            #
-            # Ajout dans la fonctionnelle d'observation
-            Jo = Jo + 0.5 * float( _YmHMX.T * RI * _YmHMX )
-        J = Jb + Jo
+            selfA.StoredVariables["CurrentState"].store( Xb + BHT * _W )
+        if selfA._toStore("SimulatedObservationAtCurrentState") or \
+            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( Hm( Xb + BHT * _W ) )
+        if selfA._toStore("InnovationAtCurrentState"):
+            selfA.StoredVariables["InnovationAtCurrentState"].store( Innovation )
+        #
+        Jb  = float( 0.5 * _W.T * HBHTpR * _W )
+        Jo  = float( - _W.T * Innovation )
+        J   = Jb + Jo
         #
         selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
         selfA.StoredVariables["CostFunctionJb"].store( Jb )
@@ -1944,38 +2038,28 @@ def std4dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
             selfA._toStore("CurrentOptimum") or \
             selfA._toStore("CostFunctionJAtCurrentOptimum") or \
             selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
-            selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+            selfA._toStore("CostFunctionJoAtCurrentOptimum") or \
+            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
             IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
         if selfA._toStore("IndexOfOptimum"):
             selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
         if selfA._toStore("CurrentOptimum"):
             selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
-        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin] )
         if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
             selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
         if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
             selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
         return J
     #
-    def GradientOfCostFunction(x):
-        _X      = numpy.asmatrix(numpy.ravel( x )).T
-        GradJb  = BI * (_X - Xb)
-        GradJo  = 0.
-        for step in range(duration-1,0,-1):
-            # Étape de récupération du dernier stockage de l'évolution
-            _Xn = selfA.DirectCalculation.pop()
-            # Étape de récupération du dernier stockage de l'innovation
-            _YmHMX = selfA.DirectInnovation.pop()
-            # Calcul des adjoints
-            Ha = HO["Adjoint"].asMatrix(ValueForMethodForm = _Xn)
-            Ha = Ha.reshape(_Xn.size,_YmHMX.size) # ADAO & check shape
-            Ma = EM["Adjoint"].asMatrix(ValueForMethodForm = _Xn)
-            Ma = Ma.reshape(_Xn.size,_Xn.size) # ADAO & check shape
-            # Calcul du gradient par état adjoint
-            GradJo = GradJo + Ha * RI * _YmHMX # Équivaut pour Ha linéaire à : Ha( (_Xn, RI * _YmHMX) )
-            GradJo = Ma * GradJo               # Équivaut pour Ma linéaire à : Ma( (_Xn, GradJo) )
-        GradJ = numpy.ravel( GradJb ) - numpy.ravel( GradJo )
+    def GradientOfCostFunction(w):
+        _W = numpy.asmatrix(numpy.ravel( w )).T
+        GradJb  = HBHTpR * _W
+        GradJo  = - Innovation
+        GradJ   = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
         return GradJ
     #
     # Minimisation de la fonctionnelle
@@ -2055,43 +2139,146 @@ def std4dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
     # ----------------------------------------------------------------
     if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
         Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
+        Minimum = numpy.asmatrix(numpy.ravel( Minimum )).T
+    else:
+        Minimum = Xb + BHT * numpy.asmatrix(numpy.ravel( Minimum )).T
     #
     # Obtention de l'analyse
     # ----------------------
-    Xa = numpy.asmatrix(numpy.ravel( Minimum )).T
+    Xa = Minimum
     #
     selfA.StoredVariables["Analysis"].store( Xa )
     #
-    # Calculs et/ou stockages supplémentaires
-    # ---------------------------------------
-    if selfA._toStore("BMA"):
-        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
-    #
-    return 0
-
-# ==============================================================================
-def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
-    """
-    Stochastic EnKF
-    """
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA._parameters["StoreInternalVariables"] = True
-    #
-    # Opérateurs
-    # ----------
-    H = HO["Direct"].appliedControledFormTo
-    #
-    if selfA._parameters["EstimationOf"] == "State":
-        M = EM["Direct"].appliedControledFormTo
-    #
-    if CM is not None and "Tangent" in CM and U is not None:
-        Cm = CM["Tangent"].asMatrix(Xb)
-    else:
-        Cm = None
+    if selfA._toStore("OMA") or \
+        selfA._toStore("SigmaObs2") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("SimulatedObservationAtOptimum"):
+        if selfA._toStore("SimulatedObservationAtCurrentState"):
+            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin]
+        elif selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"][-1]
+        else:
+            HXa = Hm( Xa )
     #
-    # Nombre de pas identique au nombre de pas d'observations
-    # -------------------------------------------------------
-    if hasattr(Y,"stepnumber"):
+    # Calcul de la covariance d'analyse
+    # ---------------------------------
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("JacobianMatrixAtOptimum") or \
+        selfA._toStore("KalmanGainAtOptimum"):
+        HtM = HO["Tangent"].asMatrix(ValueForMethodForm = Xa)
+        HtM = HtM.reshape(Y.size,Xa.size) # ADAO & check shape
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("KalmanGainAtOptimum"):
+        HaM = HO["Adjoint"].asMatrix(ValueForMethodForm = Xa)
+        HaM = HaM.reshape(Xa.size,Y.size) # ADAO & check shape
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles"):
+        BI = B.getI()
+        RI = R.getI()
+        HessienneI = []
+        nb = Xa.size
+        for i in range(nb):
+            _ee    = numpy.matrix(numpy.zeros(nb)).T
+            _ee[i] = 1.
+            _HtEE  = numpy.dot(HtM,_ee)
+            _HtEE  = numpy.asmatrix(numpy.ravel( _HtEE )).T
+            HessienneI.append( numpy.ravel( BI*_ee + HaM * (RI * _HtEE) ) )
+        HessienneI = numpy.matrix( HessienneI )
+        A = HessienneI.I
+        if min(A.shape) != max(A.shape):
+            raise ValueError("The %s a posteriori covariance matrix A is of shape %s, despites it has to be a squared matrix. There is an error in the observation operator, please check it."%(selfA._name,str(A.shape)))
+        if (numpy.diag(A) < 0).any():
+            raise ValueError("The %s a posteriori covariance matrix A has at least one negative value on its diagonal. There is an error in the observation operator, please check it."%(selfA._name,))
+        if logging.getLogger().level < logging.WARNING: # La verification n'a lieu qu'en debug
+            try:
+                L = numpy.linalg.cholesky( A )
+            except:
+                raise ValueError("The %s a posteriori covariance matrix A is not symmetric positive-definite. Please check your a priori covariances and your observation operator."%(selfA._name,))
+    if selfA._toStore("APosterioriCovariance"):
+        selfA.StoredVariables["APosterioriCovariance"].store( A )
+    if selfA._toStore("JacobianMatrixAtOptimum"):
+        selfA.StoredVariables["JacobianMatrixAtOptimum"].store( HtM )
+    if selfA._toStore("KalmanGainAtOptimum"):
+        if   (Y.size <= Xb.size): KG  = B * HaM * (R + numpy.dot(HtM, B * HaM)).I
+        elif (Y.size >  Xb.size): KG = (BI + numpy.dot(HaM, RI * HtM)).I * HaM * RI
+        selfA.StoredVariables["KalmanGainAtOptimum"].store( KG )
+    #
+    # Calculs et/ou stockages supplémentaires
+    # ---------------------------------------
+    if selfA._toStore("Innovation") or \
+        selfA._toStore("SigmaObs2") or \
+        selfA._toStore("MahalanobisConsistency") or \
+        selfA._toStore("OMB"):
+        d  = Y - HXb
+    if selfA._toStore("Innovation"):
+        selfA.StoredVariables["Innovation"].store( numpy.ravel(d) )
+    if selfA._toStore("BMA"):
+        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
+    if selfA._toStore("OMA"):
+        selfA.StoredVariables["OMA"].store( numpy.ravel(Y) - numpy.ravel(HXa) )
+    if selfA._toStore("OMB"):
+        selfA.StoredVariables["OMB"].store( numpy.ravel(d) )
+    if selfA._toStore("SigmaObs2"):
+        TraceR = R.trace(Y.size)
+        selfA.StoredVariables["SigmaObs2"].store( float( (d.T * (numpy.asmatrix(numpy.ravel(Y)).T-numpy.asmatrix(numpy.ravel(HXa)).T)) ) / TraceR )
+    if selfA._toStore("MahalanobisConsistency"):
+        selfA.StoredVariables["MahalanobisConsistency"].store( float( 2.*MinJ/d.size ) )
+    if selfA._toStore("SimulationQuantiles"):
+        nech = selfA._parameters["NumberOfSamplesForQuantiles"]
+        HXa  = numpy.matrix(numpy.ravel( HXa )).T
+        YfQ  = None
+        for i in range(nech):
+            if selfA._parameters["SimulationForQuantiles"] == "Linear":
+                dXr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A) - Xa.A1).T
+                dYr = numpy.matrix(numpy.ravel( HtM * dXr )).T
+                Yr = HXa + dYr
+            elif selfA._parameters["SimulationForQuantiles"] == "NonLinear":
+                Xr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A)).T
+                Yr = numpy.matrix(numpy.ravel( Hm( Xr ) )).T
+            if YfQ is None:
+                YfQ = Yr
+            else:
+                YfQ = numpy.hstack((YfQ,Yr))
+        YfQ.sort(axis=-1)
+        YQ = None
+        for quantile in selfA._parameters["Quantiles"]:
+            if not (0. <= float(quantile) <= 1.): continue
+            indice = int(nech * float(quantile) - 1./nech)
+            if YQ is None: YQ = YfQ[:,indice]
+            else:          YQ = numpy.hstack((YQ,YfQ[:,indice]))
+        selfA.StoredVariables["SimulationQuantiles"].store( YQ )
+    if selfA._toStore("SimulatedObservationAtBackground"):
+        selfA.StoredVariables["SimulatedObservationAtBackground"].store( numpy.ravel(HXb) )
+    if selfA._toStore("SimulatedObservationAtOptimum"):
+        selfA.StoredVariables["SimulatedObservationAtOptimum"].store( numpy.ravel(HXa) )
+    #
+    return 0
+
+# ==============================================================================
+def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
+    """
+    Stochastic EnKF
+    """
+    if selfA._parameters["EstimationOf"] == "Parameters":
+        selfA._parameters["StoreInternalVariables"] = True
+    #
+    # Opérateurs
+    # ----------
+    H = HO["Direct"].appliedControledFormTo
+    #
+    if selfA._parameters["EstimationOf"] == "State":
+        M = EM["Direct"].appliedControledFormTo
+    #
+    if CM is not None and "Tangent" in CM and U is not None:
+        Cm = CM["Tangent"].asMatrix(Xb)
+    else:
+        Cm = None
+    #
+    # Nombre de pas identique au nombre de pas d'observations
+    # -------------------------------------------------------
+    if hasattr(Y,"stepnumber"):
         duration = Y.stepnumber()
         __p = numpy.cumprod(Y.shape())[-1]
     else:
@@ -2301,834 +2488,786 @@ def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     return 0
 
 # ==============================================================================
-def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
+def std3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
     """
-    Ensemble-Transform EnKF
+    3DVAR
     """
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA._parameters["StoreInternalVariables"] = True
     #
-    # Opérateurs
-    # ----------
-    H = HO["Direct"].appliedControledFormTo
+    # Initialisations
+    # ---------------
     #
-    if selfA._parameters["EstimationOf"] == "State":
-        M = EM["Direct"].appliedControledFormTo
+    # Opérateurs
+    Hm = HO["Direct"].appliedTo
+    Ha = HO["Adjoint"].appliedInXTo
     #
-    if CM is not None and "Tangent" in CM and U is not None:
-        Cm = CM["Tangent"].asMatrix(Xb)
+    # Utilisation éventuelle d'un vecteur H(Xb) précalculé
+    if HO["AppliedInX"] is not None and "HXb" in HO["AppliedInX"]:
+        HXb = Hm( Xb, HO["AppliedInX"]["HXb"] )
     else:
-        Cm = None
+        HXb = Hm( Xb )
+    HXb = numpy.asmatrix(numpy.ravel( HXb )).T
+    if Y.size != HXb.size:
+        raise ValueError("The size %i of observations Y and %i of observed calculation H(X) are different, they have to be identical."%(Y.size,HXb.size))
+    if max(Y.shape) != max(HXb.shape):
+        raise ValueError("The shapes %s of observations Y and %s of observed calculation H(X) are different, they have to be identical."%(Y.shape,HXb.shape))
     #
-    # Nombre de pas identique au nombre de pas d'observations
-    # -------------------------------------------------------
-    if hasattr(Y,"stepnumber"):
-        duration = Y.stepnumber()
-        __p = numpy.cumprod(Y.shape())[-1]
-    else:
-        duration = 2
-        __p = numpy.array(Y).size
+    if selfA._toStore("JacobianMatrixAtBackground"):
+        HtMb = HO["Tangent"].asMatrix(ValueForMethodForm = Xb)
+        HtMb = HtMb.reshape(Y.size,Xb.size) # ADAO & check shape
+        selfA.StoredVariables["JacobianMatrixAtBackground"].store( HtMb )
     #
     # Précalcul des inversions de B et R
-    # ----------------------------------
-    if selfA._parameters["StoreInternalVariables"] \
-        or selfA._toStore("CostFunctionJ") \
-        or selfA._toStore("CostFunctionJb") \
-        or selfA._toStore("CostFunctionJo") \
-        or selfA._toStore("CurrentOptimum") \
-        or selfA._toStore("APosterioriCovariance"):
-        BI = B.getI()
-        RI = R.getI()
-    elif VariantM != "KalmanFilterFormula":
-        RI = R.getI()
-    if VariantM == "KalmanFilterFormula":
-        RIdemi = R.sqrtmI()
-    #
-    # Initialisation
-    # --------------
-    __n = Xb.size
-    __m = selfA._parameters["NumberOfMembers"]
-    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
-    else:                         Pn = B
-    if hasattr(R,"asfullmatrix"): Rn = R.asfullmatrix(__p)
-    else:                         Rn = R
-    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
-    else:                         Qn = Q
-    Xn = EnsembleOfBackgroundPerturbations( Xb, None, __m )
-    #~ Xn = EnsembleOfBackgroundPerturbations( Xb, Pn, __m )
-    #
-    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
-        selfA.StoredVariables["Analysis"].store( Xb )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
-            covarianceXa = Pn
+    BI = B.getI()
+    RI = R.getI()
     #
-    previousJMinimum = numpy.finfo(float).max
+    # Point de démarrage de l'optimisation
+    Xini = selfA._parameters["InitializationPoint"]
     #
-    for step in range(duration-1):
-        if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
-        else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,1))
-        #
-        if U is not None:
-            if hasattr(U,"store") and len(U)>1:
-                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
-            elif hasattr(U,"store") and len(U)==1:
-                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
-            else:
-                Un = numpy.asmatrix(numpy.ravel( U )).T
-        else:
-            Un = None
-        #
-        if selfA._parameters["InflationType"] == "MultiplicativeOnBackgroundAnomalies":
-            Xn = CovarianceInflation( Xn,
-                selfA._parameters["InflationType"],
-                selfA._parameters["InflationFactor"],
-                )
+    # Définition de la fonction-coût
+    # ------------------------------
+    def CostFunction(x):
+        _X  = numpy.asmatrix(numpy.ravel( x )).T
+        if selfA._parameters["StoreInternalVariables"] or \
+            selfA._toStore("CurrentState") or \
+            selfA._toStore("CurrentOptimum"):
+            selfA.StoredVariables["CurrentState"].store( _X )
+        _HX = Hm( _X )
+        _HX = numpy.asmatrix(numpy.ravel( _HX )).T
+        _Innovation = Y - _HX
+        if selfA._toStore("SimulatedObservationAtCurrentState") or \
+            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( _HX )
+        if selfA._toStore("InnovationAtCurrentState"):
+            selfA.StoredVariables["InnovationAtCurrentState"].store( _Innovation )
         #
-        if selfA._parameters["EstimationOf"] == "State": # Forecast + Q and observation of forecast
-            EMX = M( [(Xn[:,i], Un) for i in range(__m)],
-                argsAsSerie = True,
-                returnSerieAsArrayMatrix = True )
-            qi = numpy.random.multivariate_normal(numpy.zeros(__n), Qn, size=__m).T
-            Xn_predicted = EMX + qi
-            HX_predicted = H( [(Xn_predicted[:,i], Un) for i in range(__m)],
-                argsAsSerie = True,
-                returnSerieAsArrayMatrix = True )
-            if Cm is not None and Un is not None: # Attention : si Cm est aussi dans M, doublon !
-                Cm = Cm.reshape(__n,Un.size) # ADAO & check shape
-                Xn_predicted = Xn_predicted + Cm * Un
-        elif selfA._parameters["EstimationOf"] == "Parameters": # Observation of forecast
-            # --- > Par principe, M = Id, Q = 0
-            Xn_predicted = Xn
-            HX_predicted = H( [(Xn_predicted[:,i], Un) for i in range(__m)],
-                argsAsSerie = True,
-                returnSerieAsArrayMatrix = True )
+        Jb  = float( 0.5 * (_X - Xb).T * BI * (_X - Xb) )
+        Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
+        J   = Jb + Jo
         #
-        # Mean of forecast and observation of forecast
-        Xfm  = Xn_predicted.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
-        Hfm  = HX_predicted.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
-        #
-        # Anomalies
-        EaX   = EnsembleOfAnomalies( Xn_predicted )
-        EaHX  = numpy.array(HX_predicted - Hfm)
-        #
-        #--------------------------
-        if VariantM == "KalmanFilterFormula":
-            mS    = RIdemi * EaHX / math.sqrt(__m-1)
-            delta = RIdemi * ( Ynpu - Hfm )
-            mT    = numpy.linalg.inv( numpy.identity(__m) + mS.T @ mS )
-            vw    = mT @ mS.T @ delta
-            #
-            Tdemi = numpy.real(scipy.linalg.sqrtm(mT))
-            mU    = numpy.identity(__m)
-            #
-            EaX   = EaX / math.sqrt(__m-1)
-            Xn    = Xfm + EaX @ ( vw.reshape((__m,1)) + math.sqrt(__m-1) * Tdemi @ mU )
-        #--------------------------
-        elif VariantM == "Variational":
-            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
-            def CostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _Jo = 0.5 * _A.T @ (RI * _A)
-                _Jb = 0.5 * (__m-1) * w.T @ w
-                _J  = _Jo + _Jb
-                return float(_J)
-            def GradientOfCostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _GardJo = - EaHX.T @ (RI * _A)
-                _GradJb = (__m-1) * w.reshape((__m,1))
-                _GradJ  = _GardJo + _GradJb
-                return numpy.ravel(_GradJ)
-            vw = scipy.optimize.fmin_cg(
-                f           = CostFunction,
-                x0          = numpy.zeros(__m),
-                fprime      = GradientOfCostFunction,
-                args        = (),
-                disp        = False,
-                )
-            #
-            Hto = EaHX.T @ (RI * EaHX)
-            Htb = (__m-1) * numpy.identity(__m)
-            Hta = Hto + Htb
-            #
-            Pta = numpy.linalg.inv( Hta )
-            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
-            #
-            Xn  = Xfm + EaX @ (vw[:,None] + EWa)
-        #--------------------------
-        elif VariantM == "FiniteSize11": # Jauge Boc2011
-            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
-            def CostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _Jo = 0.5 * _A.T @ (RI * _A)
-                _Jb = 0.5 * __m * math.log(1 + 1/__m + w.T @ w)
-                _J  = _Jo + _Jb
-                return float(_J)
-            def GradientOfCostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _GardJo = - EaHX.T @ (RI * _A)
-                _GradJb = __m * w.reshape((__m,1)) / (1 + 1/__m + w.T @ w)
-                _GradJ  = _GardJo + _GradJb
-                return numpy.ravel(_GradJ)
-            vw = scipy.optimize.fmin_cg(
-                f           = CostFunction,
-                x0          = numpy.zeros(__m),
-                fprime      = GradientOfCostFunction,
-                args        = (),
-                disp        = False,
-                )
-            #
-            Hto = EaHX.T @ (RI * EaHX)
-            Htb = __m * \
-                ( (1 + 1/__m + vw.T @ vw) * numpy.identity(__m) - 2 * vw @ vw.T ) \
-                / (1 + 1/__m + vw.T @ vw)**2
-            Hta = Hto + Htb
-            #
-            Pta = numpy.linalg.inv( Hta )
-            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
-            #
-            Xn  = Xfm + EaX @ (vw.reshape((__m,1)) + EWa)
-        #--------------------------
-        elif VariantM == "FiniteSize15": # Jauge Boc2015
-            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
-            def CostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _Jo = 0.5 * _A.T * RI * _A
-                _Jb = 0.5 * (__m+1) * math.log(1 + 1/__m + w.T @ w)
-                _J  = _Jo + _Jb
-                return float(_J)
-            def GradientOfCostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _GardJo = - EaHX.T @ (RI * _A)
-                _GradJb = (__m+1) * w.reshape((__m,1)) / (1 + 1/__m + w.T @ w)
-                _GradJ  = _GardJo + _GradJb
-                return numpy.ravel(_GradJ)
-            vw = scipy.optimize.fmin_cg(
-                f           = CostFunction,
-                x0          = numpy.zeros(__m),
-                fprime      = GradientOfCostFunction,
-                args        = (),
-                disp        = False,
-                )
-            #
-            Hto = EaHX.T @ (RI * EaHX)
-            Htb = (__m+1) * \
-                ( (1 + 1/__m + vw.T @ vw) * numpy.identity(__m) - 2 * vw @ vw.T ) \
-                / (1 + 1/__m + vw.T @ vw)**2
-            Hta = Hto + Htb
-            #
-            Pta = numpy.linalg.inv( Hta )
-            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
-            #
-            Xn  = Xfm + EaX @ (vw.reshape((__m,1)) + EWa)
-        #--------------------------
-        elif VariantM == "FiniteSize16": # Jauge Boc2016
-            HXfm = H((Xfm[:,None], Un)) # Eventuellement Hfm
-            def CostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _Jo = 0.5 * _A.T @ (RI * _A)
-                _Jb = 0.5 * (__m+1) * math.log(1 + 1/__m + w.T @ w / (__m-1))
-                _J  = _Jo + _Jb
-                return float(_J)
-            def GradientOfCostFunction(w):
-                _A  = Ynpu - HXfm.reshape((__p,1)) - (EaHX @ w).reshape((__p,1))
-                _GardJo = - EaHX.T @ (RI * _A)
-                _GradJb = ((__m+1) / (__m-1)) * w.reshape((__m,1)) / (1 + 1/__m + w.T @ w / (__m-1))
-                _GradJ  = _GardJo + _GradJb
-                return numpy.ravel(_GradJ)
-            vw = scipy.optimize.fmin_cg(
-                f           = CostFunction,
-                x0          = numpy.zeros(__m),
-                fprime      = GradientOfCostFunction,
-                args        = (),
-                disp        = False,
-                )
-            #
-            Hto = EaHX.T @ (RI * EaHX)
-            Htb = ((__m+1) / (__m-1)) * \
-                ( (1 + 1/__m + vw.T @ vw / (__m-1)) * numpy.identity(__m) - 2 * vw @ vw.T / (__m-1) ) \
-                / (1 + 1/__m + vw.T @ vw / (__m-1))**2
-            Hta = Hto + Htb
-            #
-            Pta = numpy.linalg.inv( Hta )
-            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
-            #
-            Xn  = Xfm + EaX @ (vw[:,None] + EWa)
-        #--------------------------
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
+        selfA.StoredVariables["CostFunctionJb"].store( Jb )
+        selfA.StoredVariables["CostFunctionJo"].store( Jo )
+        selfA.StoredVariables["CostFunctionJ" ].store( J )
+        if selfA._toStore("IndexOfOptimum") or \
+            selfA._toStore("CurrentOptimum") or \
+            selfA._toStore("CostFunctionJAtCurrentOptimum") or \
+            selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
+            selfA._toStore("CostFunctionJoAtCurrentOptimum") or \
+            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+        if selfA._toStore("IndexOfOptimum"):
+            selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
+        if selfA._toStore("CurrentOptimum"):
+            selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
+        if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin] )
+        if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
+        if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        return J
+    #
+    def GradientOfCostFunction(x):
+        _X      = numpy.asmatrix(numpy.ravel( x )).T
+        _HX     = Hm( _X )
+        _HX     = numpy.asmatrix(numpy.ravel( _HX )).T
+        GradJb  = BI * (_X - Xb)
+        GradJo  = - Ha( (_X, RI * (Y - _HX)) )
+        GradJ   = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
+        return GradJ
+    #
+    # Minimisation de la fonctionnelle
+    # --------------------------------
+    nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
+    #
+    if selfA._parameters["Minimizer"] == "LBFGSB":
+        if "0.19" <= scipy.version.version <= "1.1.0":
+            import lbfgsbhlt as optimiseur
         else:
-            raise ValueError("VariantM has to be chosen in the authorized methods list.")
-        #
-        if selfA._parameters["InflationType"] == "MultiplicativeOnAnalysisAnomalies":
-            Xn = CovarianceInflation( Xn,
-                selfA._parameters["InflationType"],
-                selfA._parameters["InflationFactor"],
-                )
-        #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
-        #--------------------------
-        #
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
-            or selfA._toStore("CostFunctionJo") \
-            or selfA._toStore("APosterioriCovariance") \
-            or selfA._toStore("InnovationAtCurrentAnalysis") \
-            or selfA._toStore("SimulatedObservationAtCurrentAnalysis") \
-            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            _HXa = numpy.asmatrix(numpy.ravel( H((Xa, Un)) )).T
-            _Innovation = Ynpu - _HXa
-        #
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
-        # ---> avec analysis
-        selfA.StoredVariables["Analysis"].store( Xa )
-        if selfA._toStore("SimulatedObservationAtCurrentAnalysis"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"].store( _HXa )
-        if selfA._toStore("InnovationAtCurrentAnalysis"):
-            selfA.StoredVariables["InnovationAtCurrentAnalysis"].store( _Innovation )
-        # ---> avec current state
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CurrentState"):
-            selfA.StoredVariables["CurrentState"].store( Xn )
-        if selfA._toStore("ForecastState"):
-            selfA.StoredVariables["ForecastState"].store( EMX )
-        if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( EMX - Xa.reshape((__n,1)) )
-        if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( - HX_predicted + Ynpu )
-        if selfA._toStore("SimulatedObservationAtCurrentState") \
-            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HX_predicted )
-        # ---> autres
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
-            or selfA._toStore("CostFunctionJo") \
-            or selfA._toStore("CurrentOptimum") \
-            or selfA._toStore("APosterioriCovariance"):
-            Jb  = float( 0.5 * (Xa - Xb).T * BI * (Xa - Xb) )
-            Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
-            J   = Jb + Jo
-            selfA.StoredVariables["CostFunctionJb"].store( Jb )
-            selfA.StoredVariables["CostFunctionJo"].store( Jo )
-            selfA.StoredVariables["CostFunctionJ" ].store( J )
-            #
-            if selfA._toStore("IndexOfOptimum") \
-                or selfA._toStore("CurrentOptimum") \
-                or selfA._toStore("CostFunctionJAtCurrentOptimum") \
-                or selfA._toStore("CostFunctionJbAtCurrentOptimum") \
-                or selfA._toStore("CostFunctionJoAtCurrentOptimum") \
-                or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-                IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-            if selfA._toStore("IndexOfOptimum"):
-                selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
-            if selfA._toStore("CurrentOptimum"):
-                selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["Analysis"][IndexMin] )
-            if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-                selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"][IndexMin] )
-            if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
-            if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
-            if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
-        if selfA._parameters["EstimationOf"] == "Parameters" \
-            and J < previousJMinimum:
-            previousJMinimum    = J
-            XaMin               = Xa
-            if selfA._toStore("APosterioriCovariance"):
-                covarianceXaMin = Pn
-        # ---> Pour les smoothers
-        if selfA._toStore("CurrentEnsembleState"):
-            selfA.StoredVariables["CurrentEnsembleState"].store( Xn )
-    if selfA._toStore("LastEnsembleForecastState"):
-        selfA.StoredVariables["LastEnsembleForecastState"].store( EMX )
+            import scipy.optimize as optimiseur
+        Minimum, J_optimal, Informations = optimiseur.fmin_l_bfgs_b(
+            func        = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            bounds      = selfA._parameters["Bounds"],
+            maxfun      = selfA._parameters["MaximumNumberOfSteps"]-1,
+            factr       = selfA._parameters["CostDecrementTolerance"]*1.e14,
+            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
+            iprint      = selfA._parameters["optiprint"],
+            )
+        nfeval = Informations['funcalls']
+        rc     = Informations['warnflag']
+    elif selfA._parameters["Minimizer"] == "TNC":
+        Minimum, nfeval, rc = scipy.optimize.fmin_tnc(
+            func        = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            bounds      = selfA._parameters["Bounds"],
+            maxfun      = selfA._parameters["MaximumNumberOfSteps"],
+            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
+            ftol        = selfA._parameters["CostDecrementTolerance"],
+            messages    = selfA._parameters["optmessages"],
+            )
+    elif selfA._parameters["Minimizer"] == "CG":
+        Minimum, fopt, nfeval, grad_calls, rc = scipy.optimize.fmin_cg(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            gtol        = selfA._parameters["GradientNormTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    elif selfA._parameters["Minimizer"] == "NCG":
+        Minimum, fopt, nfeval, grad_calls, hcalls, rc = scipy.optimize.fmin_ncg(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            avextol     = selfA._parameters["CostDecrementTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    elif selfA._parameters["Minimizer"] == "BFGS":
+        Minimum, fopt, gopt, Hopt, nfeval, grad_calls, rc = scipy.optimize.fmin_bfgs(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            gtol        = selfA._parameters["GradientNormTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    else:
+        raise ValueError("Error in Minimizer name: %s"%selfA._parameters["Minimizer"])
     #
-    # Stockage final supplémentaire de l'optimum en estimation de paramètres
-    # ----------------------------------------------------------------------
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
-        selfA.StoredVariables["Analysis"].store( XaMin )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( covarianceXaMin )
-        if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(XaMin) )
+    IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+    MinJ     = selfA.StoredVariables["CostFunctionJ"][IndexMin]
+    #
+    # Correction pour pallier a un bug de TNC sur le retour du Minimum
+    # ----------------------------------------------------------------
+    if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
+        Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
+    #
+    # Obtention de l'analyse
+    # ----------------------
+    Xa = numpy.asmatrix(numpy.ravel( Minimum )).T
+    #
+    selfA.StoredVariables["Analysis"].store( Xa )
+    #
+    if selfA._toStore("OMA") or \
+        selfA._toStore("SigmaObs2") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("SimulatedObservationAtOptimum"):
+        if selfA._toStore("SimulatedObservationAtCurrentState"):
+            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin]
+        elif selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"][-1]
+        else:
+            HXa = Hm( Xa )
+    #
+    # Calcul de la covariance d'analyse
+    # ---------------------------------
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("JacobianMatrixAtOptimum") or \
+        selfA._toStore("KalmanGainAtOptimum"):
+        HtM = HO["Tangent"].asMatrix(ValueForMethodForm = Xa)
+        HtM = HtM.reshape(Y.size,Xa.size) # ADAO & check shape
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("KalmanGainAtOptimum"):
+        HaM = HO["Adjoint"].asMatrix(ValueForMethodForm = Xa)
+        HaM = HaM.reshape(Xa.size,Y.size) # ADAO & check shape
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles"):
+        HessienneI = []
+        nb = Xa.size
+        for i in range(nb):
+            _ee    = numpy.matrix(numpy.zeros(nb)).T
+            _ee[i] = 1.
+            _HtEE  = numpy.dot(HtM,_ee)
+            _HtEE  = numpy.asmatrix(numpy.ravel( _HtEE )).T
+            HessienneI.append( numpy.ravel( BI*_ee + HaM * (RI * _HtEE) ) )
+        HessienneI = numpy.matrix( HessienneI )
+        A = HessienneI.I
+        if min(A.shape) != max(A.shape):
+            raise ValueError("The %s a posteriori covariance matrix A is of shape %s, despites it has to be a squared matrix. There is an error in the observation operator, please check it."%(selfA._name,str(A.shape)))
+        if (numpy.diag(A) < 0).any():
+            raise ValueError("The %s a posteriori covariance matrix A has at least one negative value on its diagonal. There is an error in the observation operator, please check it."%(selfA._name,))
+        if logging.getLogger().level < logging.WARNING: # La verification n'a lieu qu'en debug
+            try:
+                L = numpy.linalg.cholesky( A )
+            except:
+                raise ValueError("The %s a posteriori covariance matrix A is not symmetric positive-definite. Please check your a priori covariances and your observation operator."%(selfA._name,))
+    if selfA._toStore("APosterioriCovariance"):
+        selfA.StoredVariables["APosterioriCovariance"].store( A )
+    if selfA._toStore("JacobianMatrixAtOptimum"):
+        selfA.StoredVariables["JacobianMatrixAtOptimum"].store( HtM )
+    if selfA._toStore("KalmanGainAtOptimum"):
+        if   (Y.size <= Xb.size): KG  = B * HaM * (R + numpy.dot(HtM, B * HaM)).I
+        elif (Y.size >  Xb.size): KG = (BI + numpy.dot(HaM, RI * HtM)).I * HaM * RI
+        selfA.StoredVariables["KalmanGainAtOptimum"].store( KG )
+    #
+    # Calculs et/ou stockages supplémentaires
+    # ---------------------------------------
+    if selfA._toStore("Innovation") or \
+        selfA._toStore("SigmaObs2") or \
+        selfA._toStore("MahalanobisConsistency") or \
+        selfA._toStore("OMB"):
+        d  = Y - HXb
+    if selfA._toStore("Innovation"):
+        selfA.StoredVariables["Innovation"].store( numpy.ravel(d) )
+    if selfA._toStore("BMA"):
+        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
+    if selfA._toStore("OMA"):
+        selfA.StoredVariables["OMA"].store( numpy.ravel(Y) - numpy.ravel(HXa) )
+    if selfA._toStore("OMB"):
+        selfA.StoredVariables["OMB"].store( numpy.ravel(d) )
+    if selfA._toStore("SigmaObs2"):
+        TraceR = R.trace(Y.size)
+        selfA.StoredVariables["SigmaObs2"].store( float( (d.T * (numpy.asmatrix(numpy.ravel(Y)).T-numpy.asmatrix(numpy.ravel(HXa)).T)) ) / TraceR )
+    if selfA._toStore("MahalanobisConsistency"):
+        selfA.StoredVariables["MahalanobisConsistency"].store( float( 2.*MinJ/d.size ) )
+    if selfA._toStore("SimulationQuantiles"):
+        nech = selfA._parameters["NumberOfSamplesForQuantiles"]
+        HXa  = numpy.matrix(numpy.ravel( HXa )).T
+        YfQ  = None
+        for i in range(nech):
+            if selfA._parameters["SimulationForQuantiles"] == "Linear":
+                dXr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A) - Xa.A1).T
+                dYr = numpy.matrix(numpy.ravel( HtM * dXr )).T
+                Yr = HXa + dYr
+            elif selfA._parameters["SimulationForQuantiles"] == "NonLinear":
+                Xr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A)).T
+                Yr = numpy.matrix(numpy.ravel( Hm( Xr ) )).T
+            if YfQ is None:
+                YfQ = Yr
+            else:
+                YfQ = numpy.hstack((YfQ,Yr))
+        YfQ.sort(axis=-1)
+        YQ = None
+        for quantile in selfA._parameters["Quantiles"]:
+            if not (0. <= float(quantile) <= 1.): continue
+            indice = int(nech * float(quantile) - 1./nech)
+            if YQ is None: YQ = YfQ[:,indice]
+            else:          YQ = numpy.hstack((YQ,YfQ[:,indice]))
+        selfA.StoredVariables["SimulationQuantiles"].store( YQ )
+    if selfA._toStore("SimulatedObservationAtBackground"):
+        selfA.StoredVariables["SimulatedObservationAtBackground"].store( numpy.ravel(HXb) )
+    if selfA._toStore("SimulatedObservationAtOptimum"):
+        selfA.StoredVariables["SimulatedObservationAtOptimum"].store( numpy.ravel(HXa) )
     #
     return 0
 
 # ==============================================================================
-def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
-    BnotT=False, _epsilon=1.e-3, _e=1.e-7, _jmax=15000):
+def std4dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
     """
-    Maximum Likelihood Ensemble Filter
+    4DVAR
     """
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA._parameters["StoreInternalVariables"] = True
     #
-    # Opérateurs
-    # ----------
-    H = HO["Direct"].appliedControledFormTo
+    # Initialisations
+    # ---------------
     #
-    if selfA._parameters["EstimationOf"] == "State":
-        M = EM["Direct"].appliedControledFormTo
+    # Opérateurs
+    Hm = HO["Direct"].appliedControledFormTo
+    Mm = EM["Direct"].appliedControledFormTo
     #
     if CM is not None and "Tangent" in CM and U is not None:
         Cm = CM["Tangent"].asMatrix(Xb)
     else:
         Cm = None
     #
+    def Un(_step):
+        if U is not None:
+            if hasattr(U,"store") and 1<=_step<len(U) :
+                _Un = numpy.asmatrix(numpy.ravel( U[_step] )).T
+            elif hasattr(U,"store") and len(U)==1:
+                _Un = numpy.asmatrix(numpy.ravel( U[0] )).T
+            else:
+                _Un = numpy.asmatrix(numpy.ravel( U )).T
+        else:
+            _Un = None
+        return _Un
+    def CmUn(_xn,_un):
+        if Cm is not None and _un is not None: # Attention : si Cm est aussi dans M, doublon !
+            _Cm   = Cm.reshape(_xn.size,_un.size) # ADAO & check shape
+            _CmUn = _Cm * _un
+        else:
+            _CmUn = 0.
+        return _CmUn
+    #
+    # Remarque : les observations sont exploitées à partir du pas de temps
+    # numéro 1, et sont utilisées dans Yo comme rangées selon ces indices.
+    # Donc le pas 0 n'est pas utilisé puisque la première étape commence
+    # avec l'observation du pas 1.
+    #
     # Nombre de pas identique au nombre de pas d'observations
-    # -------------------------------------------------------
     if hasattr(Y,"stepnumber"):
         duration = Y.stepnumber()
-        __p = numpy.cumprod(Y.shape())[-1]
     else:
         duration = 2
-        __p = numpy.array(Y).size
     #
     # Précalcul des inversions de B et R
-    # ----------------------------------
-    if selfA._parameters["StoreInternalVariables"] \
-        or selfA._toStore("CostFunctionJ") \
-        or selfA._toStore("CostFunctionJb") \
-        or selfA._toStore("CostFunctionJo") \
-        or selfA._toStore("CurrentOptimum") \
-        or selfA._toStore("APosterioriCovariance"):
-        BI = B.getI()
+    BI = B.getI()
     RI = R.getI()
     #
-    # Initialisation
-    # --------------
-    __n = Xb.size
-    __m = selfA._parameters["NumberOfMembers"]
-    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
-    else:                         Pn = B
-    if hasattr(R,"asfullmatrix"): Rn = R.asfullmatrix(__p)
-    else:                         Rn = R
-    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
-    else:                         Qn = Q
-    Xn = EnsembleOfBackgroundPerturbations( Xb, None, __m )
+    # Point de démarrage de l'optimisation
+    Xini = selfA._parameters["InitializationPoint"]
+    #
+    # Définition de la fonction-coût
+    # ------------------------------
+    selfA.DirectCalculation = [None,] # Le pas 0 n'est pas observé
+    selfA.DirectInnovation  = [None,] # Le pas 0 n'est pas observé
+    def CostFunction(x):
+        _X  = numpy.asmatrix(numpy.ravel( x )).T
+        if selfA._parameters["StoreInternalVariables"] or \
+            selfA._toStore("CurrentState") or \
+            selfA._toStore("CurrentOptimum"):
+            selfA.StoredVariables["CurrentState"].store( _X )
+        Jb  = float( 0.5 * (_X - Xb).T * BI * (_X - Xb) )
+        selfA.DirectCalculation = [None,]
+        selfA.DirectInnovation  = [None,]
+        Jo  = 0.
+        _Xn = _X
+        for step in range(0,duration-1):
+            if hasattr(Y,"store"):
+                _Ynpu = numpy.asmatrix(numpy.ravel( Y[step+1] )).T
+            else:
+                _Ynpu = numpy.asmatrix(numpy.ravel( Y )).T
+            _Un = Un(step)
+            #
+            # Etape d'évolution
+            if selfA._parameters["EstimationOf"] == "State":
+                _Xn = Mm( (_Xn, _Un) ) + CmUn(_Xn, _Un)
+            elif selfA._parameters["EstimationOf"] == "Parameters":
+                pass
+            #
+            if selfA._parameters["Bounds"] is not None and selfA._parameters["ConstrainedBy"] == "EstimateProjection":
+                _Xn = numpy.max(numpy.hstack((_Xn,numpy.asmatrix(selfA._parameters["Bounds"])[:,0])),axis=1)
+                _Xn = numpy.min(numpy.hstack((_Xn,numpy.asmatrix(selfA._parameters["Bounds"])[:,1])),axis=1)
+            #
+            # Etape de différence aux observations
+            if selfA._parameters["EstimationOf"] == "State":
+                _YmHMX = _Ynpu - numpy.asmatrix(numpy.ravel( Hm( (_Xn, None) ) )).T
+            elif selfA._parameters["EstimationOf"] == "Parameters":
+                _YmHMX = _Ynpu - numpy.asmatrix(numpy.ravel( Hm( (_Xn, _Un) ) )).T - CmUn(_Xn, _Un)
+            #
+            # Stockage de l'état
+            selfA.DirectCalculation.append( _Xn )
+            selfA.DirectInnovation.append( _YmHMX )
+            #
+            # Ajout dans la fonctionnelle d'observation
+            Jo = Jo + 0.5 * float( _YmHMX.T * RI * _YmHMX )
+        J = Jb + Jo
+        #
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
+        selfA.StoredVariables["CostFunctionJb"].store( Jb )
+        selfA.StoredVariables["CostFunctionJo"].store( Jo )
+        selfA.StoredVariables["CostFunctionJ" ].store( J )
+        if selfA._toStore("IndexOfOptimum") or \
+            selfA._toStore("CurrentOptimum") or \
+            selfA._toStore("CostFunctionJAtCurrentOptimum") or \
+            selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
+            selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+            IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+        if selfA._toStore("IndexOfOptimum"):
+            selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
+        if selfA._toStore("CurrentOptimum"):
+            selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
+        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
+        if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+        return J
     #
-    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
-        selfA.StoredVariables["Analysis"].store( Xb )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
-            covarianceXa = Pn
+    def GradientOfCostFunction(x):
+        _X      = numpy.asmatrix(numpy.ravel( x )).T
+        GradJb  = BI * (_X - Xb)
+        GradJo  = 0.
+        for step in range(duration-1,0,-1):
+            # Étape de récupération du dernier stockage de l'évolution
+            _Xn = selfA.DirectCalculation.pop()
+            # Étape de récupération du dernier stockage de l'innovation
+            _YmHMX = selfA.DirectInnovation.pop()
+            # Calcul des adjoints
+            Ha = HO["Adjoint"].asMatrix(ValueForMethodForm = _Xn)
+            Ha = Ha.reshape(_Xn.size,_YmHMX.size) # ADAO & check shape
+            Ma = EM["Adjoint"].asMatrix(ValueForMethodForm = _Xn)
+            Ma = Ma.reshape(_Xn.size,_Xn.size) # ADAO & check shape
+            # Calcul du gradient par état adjoint
+            GradJo = GradJo + Ha * RI * _YmHMX # Équivaut pour Ha linéaire à : Ha( (_Xn, RI * _YmHMX) )
+            GradJo = Ma * GradJo               # Équivaut pour Ma linéaire à : Ma( (_Xn, GradJo) )
+        GradJ = numpy.ravel( GradJb ) - numpy.ravel( GradJo )
+        return GradJ
     #
-    previousJMinimum = numpy.finfo(float).max
+    # Minimisation de la fonctionnelle
+    # --------------------------------
+    nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
     #
-    for step in range(duration-1):
-        if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
-        else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,1))
-        #
-        if U is not None:
-            if hasattr(U,"store") and len(U)>1:
-                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
-            elif hasattr(U,"store") and len(U)==1:
-                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
-            else:
-                Un = numpy.asmatrix(numpy.ravel( U )).T
-        else:
-            Un = None
-        #
-        if selfA._parameters["InflationType"] == "MultiplicativeOnBackgroundAnomalies":
-            Xn = CovarianceInflation( Xn,
-                selfA._parameters["InflationType"],
-                selfA._parameters["InflationFactor"],
-                )
-        #
-        if selfA._parameters["EstimationOf"] == "State": # Forecast + Q and observation of forecast
-            EMX = M( [(Xn[:,i], Un) for i in range(__m)],
-                argsAsSerie = True,
-                returnSerieAsArrayMatrix = True )
-            qi = numpy.random.multivariate_normal(numpy.zeros(__n), Qn, size=__m).T
-            Xn_predicted = EMX + qi
-            if Cm is not None and Un is not None: # Attention : si Cm est aussi dans M, doublon !
-                Cm = Cm.reshape(__n,Un.size) # ADAO & check shape
-                Xn_predicted = Xn_predicted + Cm * Un
-        elif selfA._parameters["EstimationOf"] == "Parameters": # Observation of forecast
-            # --- > Par principe, M = Id, Q = 0
-            Xn_predicted = Xn
-        #
-        #--------------------------
-        if VariantM == "MLEF13":
-            Xfm = numpy.ravel(Xn_predicted.mean(axis=1, dtype=mfp).astype('float'))
-            EaX = EnsembleOfAnomalies( Xn_predicted, Xfm, 1./math.sqrt(__m-1) )
-            Ua  = numpy.identity(__m)
-            __j = 0
-            Deltaw = 1
-            if not BnotT:
-                Ta  = numpy.identity(__m)
-            vw  = numpy.zeros(__m)
-            while numpy.linalg.norm(Deltaw) >= _e and __j <= _jmax:
-                vx1 = (Xfm + EaX @ vw).reshape((__n,1))
-                #
-                if BnotT:
-                    E1 = vx1 + _epsilon * EaX
-                else:
-                    E1 = vx1 + math.sqrt(__m-1) * EaX @ Ta
-                #
-                HE2 = H( [(E1[:,i,numpy.newaxis], Un) for i in range(__m)],
-                    argsAsSerie = True,
-                    returnSerieAsArrayMatrix = True )
-                vy2 = HE2.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
-                #
-                if BnotT:
-                    EaY = (HE2 - vy2) / _epsilon
-                else:
-                    EaY = ( (HE2 - vy2) @ numpy.linalg.inv(Ta) ) / math.sqrt(__m-1)
-                #
-                GradJ = numpy.ravel(vw[:,None] - EaY.transpose() @ (RI * ( Ynpu - vy2 )))
-                mH = numpy.identity(__m) + EaY.transpose() @ (RI * EaY)
-                Deltaw = - numpy.linalg.solve(mH,GradJ)
-                #
-                vw = vw + Deltaw
-                #
-                if not BnotT:
-                    Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
-                #
-                __j = __j + 1
-            #
-            if BnotT:
-                Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
-            #
-            Xn = vx1 + math.sqrt(__m-1) * EaX @ Ta @ Ua
-        #--------------------------
+    if selfA._parameters["Minimizer"] == "LBFGSB":
+        if "0.19" <= scipy.version.version <= "1.1.0":
+            import lbfgsbhlt as optimiseur
         else:
-            raise ValueError("VariantM has to be chosen in the authorized methods list.")
-        #
-        if selfA._parameters["InflationType"] == "MultiplicativeOnAnalysisAnomalies":
-            Xn = CovarianceInflation( Xn,
-                selfA._parameters["InflationType"],
-                selfA._parameters["InflationFactor"],
-                )
-        #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
-        #--------------------------
-        #
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
-            or selfA._toStore("CostFunctionJo") \
-            or selfA._toStore("APosterioriCovariance") \
-            or selfA._toStore("InnovationAtCurrentAnalysis") \
-            or selfA._toStore("SimulatedObservationAtCurrentAnalysis") \
-            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            _HXa = numpy.asmatrix(numpy.ravel( H((Xa, Un)) )).T
-            _Innovation = Ynpu - _HXa
-        #
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
-        # ---> avec analysis
-        selfA.StoredVariables["Analysis"].store( Xa )
-        if selfA._toStore("SimulatedObservationAtCurrentAnalysis"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"].store( _HXa )
-        if selfA._toStore("InnovationAtCurrentAnalysis"):
-            selfA.StoredVariables["InnovationAtCurrentAnalysis"].store( _Innovation )
-        # ---> avec current state
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CurrentState"):
-            selfA.StoredVariables["CurrentState"].store( Xn )
-        if selfA._toStore("ForecastState"):
-            selfA.StoredVariables["ForecastState"].store( EMX )
-        if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( EMX - Xa )
-        if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu )
-        if selfA._toStore("SimulatedObservationAtCurrentState") \
-            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
-        # ---> autres
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
-            or selfA._toStore("CostFunctionJo") \
-            or selfA._toStore("CurrentOptimum") \
-            or selfA._toStore("APosterioriCovariance"):
-            Jb  = float( 0.5 * (Xa - Xb).T * BI * (Xa - Xb) )
-            Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
-            J   = Jb + Jo
-            selfA.StoredVariables["CostFunctionJb"].store( Jb )
-            selfA.StoredVariables["CostFunctionJo"].store( Jo )
-            selfA.StoredVariables["CostFunctionJ" ].store( J )
-            #
-            if selfA._toStore("IndexOfOptimum") \
-                or selfA._toStore("CurrentOptimum") \
-                or selfA._toStore("CostFunctionJAtCurrentOptimum") \
-                or selfA._toStore("CostFunctionJbAtCurrentOptimum") \
-                or selfA._toStore("CostFunctionJoAtCurrentOptimum") \
-                or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-                IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-            if selfA._toStore("IndexOfOptimum"):
-                selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
-            if selfA._toStore("CurrentOptimum"):
-                selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["Analysis"][IndexMin] )
-            if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-                selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"][IndexMin] )
-            if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
-            if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
-            if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
-        if selfA._parameters["EstimationOf"] == "Parameters" \
-            and J < previousJMinimum:
-            previousJMinimum    = J
-            XaMin               = Xa
-            if selfA._toStore("APosterioriCovariance"):
-                covarianceXaMin = Pn
+            import scipy.optimize as optimiseur
+        Minimum, J_optimal, Informations = optimiseur.fmin_l_bfgs_b(
+            func        = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            bounds      = selfA._parameters["Bounds"],
+            maxfun      = selfA._parameters["MaximumNumberOfSteps"]-1,
+            factr       = selfA._parameters["CostDecrementTolerance"]*1.e14,
+            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
+            iprint      = selfA._parameters["optiprint"],
+            )
+        nfeval = Informations['funcalls']
+        rc     = Informations['warnflag']
+    elif selfA._parameters["Minimizer"] == "TNC":
+        Minimum, nfeval, rc = scipy.optimize.fmin_tnc(
+            func        = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            bounds      = selfA._parameters["Bounds"],
+            maxfun      = selfA._parameters["MaximumNumberOfSteps"],
+            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
+            ftol        = selfA._parameters["CostDecrementTolerance"],
+            messages    = selfA._parameters["optmessages"],
+            )
+    elif selfA._parameters["Minimizer"] == "CG":
+        Minimum, fopt, nfeval, grad_calls, rc = scipy.optimize.fmin_cg(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            gtol        = selfA._parameters["GradientNormTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    elif selfA._parameters["Minimizer"] == "NCG":
+        Minimum, fopt, nfeval, grad_calls, hcalls, rc = scipy.optimize.fmin_ncg(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            avextol     = selfA._parameters["CostDecrementTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    elif selfA._parameters["Minimizer"] == "BFGS":
+        Minimum, fopt, gopt, Hopt, nfeval, grad_calls, rc = scipy.optimize.fmin_bfgs(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            gtol        = selfA._parameters["GradientNormTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    else:
+        raise ValueError("Error in Minimizer name: %s"%selfA._parameters["Minimizer"])
     #
-    # Stockage final supplémentaire de l'optimum en estimation de paramètres
-    # ----------------------------------------------------------------------
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
-        selfA.StoredVariables["Analysis"].store( XaMin )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( covarianceXaMin )
-        if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(XaMin) )
+    IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+    MinJ     = selfA.StoredVariables["CostFunctionJ"][IndexMin]
+    #
+    # Correction pour pallier a un bug de TNC sur le retour du Minimum
+    # ----------------------------------------------------------------
+    if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
+        Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
+    #
+    # Obtention de l'analyse
+    # ----------------------
+    Xa = numpy.asmatrix(numpy.ravel( Minimum )).T
+    #
+    selfA.StoredVariables["Analysis"].store( Xa )
+    #
+    # Calculs et/ou stockages supplémentaires
+    # ---------------------------------------
+    if selfA._toStore("BMA"):
+        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
     #
     return 0
 
 # ==============================================================================
-def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
-    BnotT=False, _epsilon=1.e-3, _e=1.e-7, _jmax=15000):
+def van3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
     """
-    Iterative EnKF
+    3DVAR variational analysis with no inversion of B
     """
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA._parameters["StoreInternalVariables"] = True
-    #
-    # Opérateurs
-    # ----------
-    H = HO["Direct"].appliedControledFormTo
-    #
-    if selfA._parameters["EstimationOf"] == "State":
-        M = EM["Direct"].appliedControledFormTo
     #
-    if CM is not None and "Tangent" in CM and U is not None:
-        Cm = CM["Tangent"].asMatrix(Xb)
-    else:
-        Cm = None
+    # Initialisations
+    # ---------------
     #
-    # Nombre de pas identique au nombre de pas d'observations
-    # -------------------------------------------------------
-    if hasattr(Y,"stepnumber"):
-        duration = Y.stepnumber()
-        __p = numpy.cumprod(Y.shape())[-1]
-    else:
-        duration = 2
-        __p = numpy.array(Y).size
+    # Opérateurs
+    Hm = HO["Direct"].appliedTo
+    Ha = HO["Adjoint"].appliedInXTo
     #
     # Précalcul des inversions de B et R
-    # ----------------------------------
-    if selfA._parameters["StoreInternalVariables"] \
-        or selfA._toStore("CostFunctionJ") \
-        or selfA._toStore("CostFunctionJb") \
-        or selfA._toStore("CostFunctionJo") \
-        or selfA._toStore("CurrentOptimum") \
-        or selfA._toStore("APosterioriCovariance"):
-        BI = B.getI()
+    BT = B.getT()
     RI = R.getI()
     #
-    # Initialisation
-    # --------------
-    __n = Xb.size
-    __m = selfA._parameters["NumberOfMembers"]
-    if hasattr(B,"asfullmatrix"): Pn = B.asfullmatrix(__n)
-    else:                         Pn = B
-    if hasattr(R,"asfullmatrix"): Rn = R.asfullmatrix(__p)
-    else:                         Rn = R
-    if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
-    else:                         Qn = Q
-    Xn = EnsembleOfBackgroundPerturbations( Xb, Pn, __m )
+    # Point de démarrage de l'optimisation
+    Xini = numpy.zeros(Xb.shape)
     #
-    if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
-        selfA.StoredVariables["Analysis"].store( Xb )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
-            covarianceXa = Pn
+    # Définition de la fonction-coût
+    # ------------------------------
+    def CostFunction(v):
+        _V = numpy.asmatrix(numpy.ravel( v )).T
+        _X = Xb + B * _V
+        if selfA._parameters["StoreInternalVariables"] or \
+            selfA._toStore("CurrentState") or \
+            selfA._toStore("CurrentOptimum"):
+            selfA.StoredVariables["CurrentState"].store( _X )
+        _HX = Hm( _X )
+        _HX = numpy.asmatrix(numpy.ravel( _HX )).T
+        _Innovation = Y - _HX
+        if selfA._toStore("SimulatedObservationAtCurrentState") or \
+            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( _HX )
+        if selfA._toStore("InnovationAtCurrentState"):
+            selfA.StoredVariables["InnovationAtCurrentState"].store( _Innovation )
+        #
+        Jb  = float( 0.5 * _V.T * BT * _V )
+        Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
+        J   = Jb + Jo
+        #
+        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["CostFunctionJ"]) )
+        selfA.StoredVariables["CostFunctionJb"].store( Jb )
+        selfA.StoredVariables["CostFunctionJo"].store( Jo )
+        selfA.StoredVariables["CostFunctionJ" ].store( J )
+        if selfA._toStore("IndexOfOptimum") or \
+            selfA._toStore("CurrentOptimum") or \
+            selfA._toStore("CostFunctionJAtCurrentOptimum") or \
+            selfA._toStore("CostFunctionJbAtCurrentOptimum") or \
+            selfA._toStore("CostFunctionJoAtCurrentOptimum") or \
+            selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+        if selfA._toStore("IndexOfOptimum"):
+            selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
+        if selfA._toStore("CurrentOptimum"):
+            selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["CurrentState"][IndexMin] )
+        if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin] )
+        if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
+        if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
+        if selfA._toStore("CostFunctionJAtCurrentOptimum"):
+            selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
+        return J
     #
-    previousJMinimum = numpy.finfo(float).max
+    def GradientOfCostFunction(v):
+        _V = numpy.asmatrix(numpy.ravel( v )).T
+        _X = Xb + B * _V
+        _HX     = Hm( _X )
+        _HX     = numpy.asmatrix(numpy.ravel( _HX )).T
+        GradJb  = BT * _V
+        GradJo  = - Ha( (_X, RI * (Y - _HX)) )
+        GradJ   = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
+        return GradJ
     #
-    for step in range(duration-1):
-        if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
-        else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,1))
-        #
-        if U is not None:
-            if hasattr(U,"store") and len(U)>1:
-                Un = numpy.asmatrix(numpy.ravel( U[step] )).T
-            elif hasattr(U,"store") and len(U)==1:
-                Un = numpy.asmatrix(numpy.ravel( U[0] )).T
-            else:
-                Un = numpy.asmatrix(numpy.ravel( U )).T
+    # Minimisation de la fonctionnelle
+    # --------------------------------
+    nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
+    #
+    if selfA._parameters["Minimizer"] == "LBFGSB":
+        if "0.19" <= scipy.version.version <= "1.1.0":
+            import lbfgsbhlt as optimiseur
         else:
-            Un = None
-        #
-        if selfA._parameters["InflationType"] == "MultiplicativeOnBackgroundAnomalies":
-            Xn = CovarianceInflation( Xn,
-                selfA._parameters["InflationType"],
-                selfA._parameters["InflationFactor"],
-                )
-        #
-        #--------------------------
-        if VariantM == "IEnKF12":
-            Xfm = numpy.ravel(Xn.mean(axis=1, dtype=mfp).astype('float'))
-            EaX = EnsembleOfAnomalies( Xn ) / math.sqrt(__m-1)
-            __j = 0
-            Deltaw = 1
-            if not BnotT:
-                Ta  = numpy.identity(__m)
-            vw  = numpy.zeros(__m)
-            while numpy.linalg.norm(Deltaw) >= _e and __j <= _jmax:
-                vx1 = (Xfm + EaX @ vw).reshape((__n,1))
-                #
-                if BnotT:
-                    E1 = vx1 + _epsilon * EaX
-                else:
-                    E1 = vx1 + math.sqrt(__m-1) * EaX @ Ta
-                #
-                if selfA._parameters["EstimationOf"] == "State": # Forecast + Q
-                    E2 = M( [(E1[:,i,numpy.newaxis], Un) for i in range(__m)],
-                        argsAsSerie = True,
-                        returnSerieAsArrayMatrix = True )
-                elif selfA._parameters["EstimationOf"] == "Parameters":
-                    # --- > Par principe, M = Id
-                    E2 = Xn
-                vx2 = E2.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
-                vy1 = H((vx2, Un)).reshape((__p,1))
-                #
-                HE2 = H( [(E2[:,i,numpy.newaxis], Un) for i in range(__m)],
-                    argsAsSerie = True,
-                    returnSerieAsArrayMatrix = True )
-                vy2 = HE2.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
-                #
-                if BnotT:
-                    EaY = (HE2 - vy2) / _epsilon
-                else:
-                    EaY = ( (HE2 - vy2) @ numpy.linalg.inv(Ta) ) / math.sqrt(__m-1)
-                #
-                GradJ = numpy.ravel(vw[:,None] - EaY.transpose() @ (RI * ( Ynpu - vy1 )))
-                mH = numpy.identity(__m) + EaY.transpose() @ (RI * EaY)
-                Deltaw = - numpy.linalg.solve(mH,GradJ)
-                #
-                vw = vw + Deltaw
-                #
-                if not BnotT:
-                    Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
-                #
-                __j = __j + 1
-            #
-            A2 = EnsembleOfAnomalies( E2 )
-            #
-            if BnotT:
-                Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
-                A2 = math.sqrt(__m-1) * A2 @ Ta / _epsilon
-            #
-            Xn = vx2 + A2
-        #--------------------------
+            import scipy.optimize as optimiseur
+        Minimum, J_optimal, Informations = optimiseur.fmin_l_bfgs_b(
+            func        = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            bounds      = selfA._parameters["Bounds"],
+            maxfun      = selfA._parameters["MaximumNumberOfSteps"]-1,
+            factr       = selfA._parameters["CostDecrementTolerance"]*1.e14,
+            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
+            iprint      = selfA._parameters["optiprint"],
+            )
+        nfeval = Informations['funcalls']
+        rc     = Informations['warnflag']
+    elif selfA._parameters["Minimizer"] == "TNC":
+        Minimum, nfeval, rc = scipy.optimize.fmin_tnc(
+            func        = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            bounds      = selfA._parameters["Bounds"],
+            maxfun      = selfA._parameters["MaximumNumberOfSteps"],
+            pgtol       = selfA._parameters["ProjectedGradientTolerance"],
+            ftol        = selfA._parameters["CostDecrementTolerance"],
+            messages    = selfA._parameters["optmessages"],
+            )
+    elif selfA._parameters["Minimizer"] == "CG":
+        Minimum, fopt, nfeval, grad_calls, rc = scipy.optimize.fmin_cg(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            gtol        = selfA._parameters["GradientNormTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    elif selfA._parameters["Minimizer"] == "NCG":
+        Minimum, fopt, nfeval, grad_calls, hcalls, rc = scipy.optimize.fmin_ncg(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            avextol     = selfA._parameters["CostDecrementTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    elif selfA._parameters["Minimizer"] == "BFGS":
+        Minimum, fopt, gopt, Hopt, nfeval, grad_calls, rc = scipy.optimize.fmin_bfgs(
+            f           = CostFunction,
+            x0          = Xini,
+            fprime      = GradientOfCostFunction,
+            args        = (),
+            maxiter     = selfA._parameters["MaximumNumberOfSteps"],
+            gtol        = selfA._parameters["GradientNormTolerance"],
+            disp        = selfA._parameters["optdisp"],
+            full_output = True,
+            )
+    else:
+        raise ValueError("Error in Minimizer name: %s"%selfA._parameters["Minimizer"])
+    #
+    IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
+    MinJ     = selfA.StoredVariables["CostFunctionJ"][IndexMin]
+    #
+    # Correction pour pallier a un bug de TNC sur le retour du Minimum
+    # ----------------------------------------------------------------
+    if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
+        Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
+        Minimum = numpy.asmatrix(numpy.ravel( Minimum )).T
+    else:
+        Minimum = Xb + B * numpy.asmatrix(numpy.ravel( Minimum )).T
+    #
+    # Obtention de l'analyse
+    # ----------------------
+    Xa = Minimum
+    #
+    selfA.StoredVariables["Analysis"].store( Xa )
+    #
+    if selfA._toStore("OMA") or \
+        selfA._toStore("SigmaObs2") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("SimulatedObservationAtOptimum"):
+        if selfA._toStore("SimulatedObservationAtCurrentState"):
+            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentState"][IndexMin]
+        elif selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+            HXa = selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"][-1]
         else:
-            raise ValueError("VariantM has to be chosen in the authorized methods list.")
-        #
-        if selfA._parameters["InflationType"] == "MultiplicativeOnAnalysisAnomalies":
-            Xn = CovarianceInflation( Xn,
-                selfA._parameters["InflationType"],
-                selfA._parameters["InflationFactor"],
-                )
-        #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
-        #--------------------------
-        #
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
-            or selfA._toStore("CostFunctionJo") \
-            or selfA._toStore("APosterioriCovariance") \
-            or selfA._toStore("InnovationAtCurrentAnalysis") \
-            or selfA._toStore("SimulatedObservationAtCurrentAnalysis") \
-            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            _HXa = numpy.asmatrix(numpy.ravel( H((Xa, Un)) )).T
-            _Innovation = Ynpu - _HXa
-        #
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
-        # ---> avec analysis
-        selfA.StoredVariables["Analysis"].store( Xa )
-        if selfA._toStore("SimulatedObservationAtCurrentAnalysis"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"].store( _HXa )
-        if selfA._toStore("InnovationAtCurrentAnalysis"):
-            selfA.StoredVariables["InnovationAtCurrentAnalysis"].store( _Innovation )
-        # ---> avec current state
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CurrentState"):
-            selfA.StoredVariables["CurrentState"].store( Xn )
-        if selfA._toStore("ForecastState"):
-            selfA.StoredVariables["ForecastState"].store( E2 )
-        if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( E2 - Xa )
-        if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu )
-        if selfA._toStore("SimulatedObservationAtCurrentState") \
-            or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
-        # ---> autres
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
-            or selfA._toStore("CostFunctionJo") \
-            or selfA._toStore("CurrentOptimum") \
-            or selfA._toStore("APosterioriCovariance"):
-            Jb  = float( 0.5 * (Xa - Xb).T * BI * (Xa - Xb) )
-            Jo  = float( 0.5 * _Innovation.T * RI * _Innovation )
-            J   = Jb + Jo
-            selfA.StoredVariables["CostFunctionJb"].store( Jb )
-            selfA.StoredVariables["CostFunctionJo"].store( Jo )
-            selfA.StoredVariables["CostFunctionJ" ].store( J )
-            #
-            if selfA._toStore("IndexOfOptimum") \
-                or selfA._toStore("CurrentOptimum") \
-                or selfA._toStore("CostFunctionJAtCurrentOptimum") \
-                or selfA._toStore("CostFunctionJbAtCurrentOptimum") \
-                or selfA._toStore("CostFunctionJoAtCurrentOptimum") \
-                or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-                IndexMin = numpy.argmin( selfA.StoredVariables["CostFunctionJ"][nbPreviousSteps:] ) + nbPreviousSteps
-            if selfA._toStore("IndexOfOptimum"):
-                selfA.StoredVariables["IndexOfOptimum"].store( IndexMin )
-            if selfA._toStore("CurrentOptimum"):
-                selfA.StoredVariables["CurrentOptimum"].store( selfA.StoredVariables["Analysis"][IndexMin] )
-            if selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-                selfA.StoredVariables["SimulatedObservationAtCurrentOptimum"].store( selfA.StoredVariables["SimulatedObservationAtCurrentAnalysis"][IndexMin] )
-            if selfA._toStore("CostFunctionJbAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJbAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJb"][IndexMin] )
-            if selfA._toStore("CostFunctionJoAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJoAtCurrentOptimum"].store( selfA.StoredVariables["CostFunctionJo"][IndexMin] )
-            if selfA._toStore("CostFunctionJAtCurrentOptimum"):
-                selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
-        if selfA._parameters["EstimationOf"] == "Parameters" \
-            and J < previousJMinimum:
-            previousJMinimum    = J
-            XaMin               = Xa
-            if selfA._toStore("APosterioriCovariance"):
-                covarianceXaMin = Pn
+            HXa = Hm( Xa )
     #
-    # Stockage final supplémentaire de l'optimum en estimation de paramètres
-    # ----------------------------------------------------------------------
-    if selfA._parameters["EstimationOf"] == "Parameters":
-        selfA.StoredVariables["CurrentIterationNumber"].store( len(selfA.StoredVariables["Analysis"]) )
-        selfA.StoredVariables["Analysis"].store( XaMin )
-        if selfA._toStore("APosterioriCovariance"):
-            selfA.StoredVariables["APosterioriCovariance"].store( covarianceXaMin )
-        if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(XaMin) )
+    # Calcul de la covariance d'analyse
+    # ---------------------------------
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("JacobianMatrixAtOptimum") or \
+        selfA._toStore("KalmanGainAtOptimum"):
+        HtM = HO["Tangent"].asMatrix(ValueForMethodForm = Xa)
+        HtM = HtM.reshape(Y.size,Xa.size) # ADAO & check shape
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles") or \
+        selfA._toStore("KalmanGainAtOptimum"):
+        HaM = HO["Adjoint"].asMatrix(ValueForMethodForm = Xa)
+        HaM = HaM.reshape(Xa.size,Y.size) # ADAO & check shape
+    if selfA._toStore("APosterioriCovariance") or \
+        selfA._toStore("SimulationQuantiles"):
+        BI = B.getI()
+        HessienneI = []
+        nb = Xa.size
+        for i in range(nb):
+            _ee    = numpy.matrix(numpy.zeros(nb)).T
+            _ee[i] = 1.
+            _HtEE  = numpy.dot(HtM,_ee)
+            _HtEE  = numpy.asmatrix(numpy.ravel( _HtEE )).T
+            HessienneI.append( numpy.ravel( BI*_ee + HaM * (RI * _HtEE) ) )
+        HessienneI = numpy.matrix( HessienneI )
+        A = HessienneI.I
+        if min(A.shape) != max(A.shape):
+            raise ValueError("The %s a posteriori covariance matrix A is of shape %s, despites it has to be a squared matrix. There is an error in the observation operator, please check it."%(selfA._name,str(A.shape)))
+        if (numpy.diag(A) < 0).any():
+            raise ValueError("The %s a posteriori covariance matrix A has at least one negative value on its diagonal. There is an error in the observation operator, please check it."%(selfA._name,))
+        if logging.getLogger().level < logging.WARNING: # La verification n'a lieu qu'en debug
+            try:
+                L = numpy.linalg.cholesky( A )
+            except:
+                raise ValueError("The %s a posteriori covariance matrix A is not symmetric positive-definite. Please check your a priori covariances and your observation operator."%(selfA._name,))
+    if selfA._toStore("APosterioriCovariance"):
+        selfA.StoredVariables["APosterioriCovariance"].store( A )
+    if selfA._toStore("JacobianMatrixAtOptimum"):
+        selfA.StoredVariables["JacobianMatrixAtOptimum"].store( HtM )
+    if selfA._toStore("KalmanGainAtOptimum"):
+        if   (Y.size <= Xb.size): KG  = B * HaM * (R + numpy.dot(HtM, B * HaM)).I
+        elif (Y.size >  Xb.size): KG = (BI + numpy.dot(HaM, RI * HtM)).I * HaM * RI
+        selfA.StoredVariables["KalmanGainAtOptimum"].store( KG )
+    #
+    # Calculs et/ou stockages supplémentaires
+    # ---------------------------------------
+    if selfA._toStore("Innovation") or \
+        selfA._toStore("SigmaObs2") or \
+        selfA._toStore("MahalanobisConsistency") or \
+        selfA._toStore("OMB"):
+        d  = Y - HXb
+    if selfA._toStore("Innovation"):
+        selfA.StoredVariables["Innovation"].store( numpy.ravel(d) )
+    if selfA._toStore("BMA"):
+        selfA.StoredVariables["BMA"].store( numpy.ravel(Xb) - numpy.ravel(Xa) )
+    if selfA._toStore("OMA"):
+        selfA.StoredVariables["OMA"].store( numpy.ravel(Y) - numpy.ravel(HXa) )
+    if selfA._toStore("OMB"):
+        selfA.StoredVariables["OMB"].store( numpy.ravel(d) )
+    if selfA._toStore("SigmaObs2"):
+        TraceR = R.trace(Y.size)
+        selfA.StoredVariables["SigmaObs2"].store( float( (d.T * (numpy.asmatrix(numpy.ravel(Y)).T-numpy.asmatrix(numpy.ravel(HXa)).T)) ) / TraceR )
+    if selfA._toStore("MahalanobisConsistency"):
+        selfA.StoredVariables["MahalanobisConsistency"].store( float( 2.*MinJ/d.size ) )
+    if selfA._toStore("SimulationQuantiles"):
+        nech = selfA._parameters["NumberOfSamplesForQuantiles"]
+        HXa  = numpy.matrix(numpy.ravel( HXa )).T
+        YfQ  = None
+        for i in range(nech):
+            if selfA._parameters["SimulationForQuantiles"] == "Linear":
+                dXr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A) - Xa.A1).T
+                dYr = numpy.matrix(numpy.ravel( HtM * dXr )).T
+                Yr = HXa + dYr
+            elif selfA._parameters["SimulationForQuantiles"] == "NonLinear":
+                Xr = numpy.matrix(numpy.random.multivariate_normal(Xa.A1,A)).T
+                Yr = numpy.matrix(numpy.ravel( Hm( Xr ) )).T
+            if YfQ is None:
+                YfQ = Yr
+            else:
+                YfQ = numpy.hstack((YfQ,Yr))
+        YfQ.sort(axis=-1)
+        YQ = None
+        for quantile in selfA._parameters["Quantiles"]:
+            if not (0. <= float(quantile) <= 1.): continue
+            indice = int(nech * float(quantile) - 1./nech)
+            if YQ is None: YQ = YfQ[:,indice]
+            else:          YQ = numpy.hstack((YQ,YfQ[:,indice]))
+        selfA.StoredVariables["SimulationQuantiles"].store( YQ )
+    if selfA._toStore("SimulatedObservationAtBackground"):
+        selfA.StoredVariables["SimulatedObservationAtBackground"].store( numpy.ravel(HXb) )
+    if selfA._toStore("SimulatedObservationAtOptimum"):
+        selfA.StoredVariables["SimulatedObservationAtOptimum"].store( numpy.ravel(HXa) )
     #
     return 0