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Improvement and extension of EnKF algorithm (EnKS)
[modules/adao.git] / src / daComposant / daCore / NumericObjects.py
index 7571a15d8ea4c745fbdeb93caa10186df6bf4834..5089c21f3ef060896e8739797cad63995898096f 100644 (file)
@@ -26,7 +26,7 @@ __doc__ = """
 __author__ = "Jean-Philippe ARGAUD"
 
 import os, time, copy, types, sys, logging
-import math, numpy, scipy, scipy.optimize
+import math, numpy, scipy, scipy.optimize, scipy.version
 from daCore.BasicObjects import Operator
 from daCore.PlatformInfo import PlatformInfo
 mpr = PlatformInfo().MachinePrecision()
@@ -34,15 +34,18 @@ mfp = PlatformInfo().MaximumPrecision()
 # logging.getLogger().setLevel(logging.DEBUG)
 
 # ==============================================================================
-def ExecuteFunction( paire ):
-    assert len(paire) == 2, "Incorrect number of arguments"
-    X, funcrepr = paire
+def ExecuteFunction( triplet ):
+    assert len(triplet) == 3, "Incorrect number of arguments"
+    X, xArgs, funcrepr = triplet
     __X = numpy.asmatrix(numpy.ravel( X )).T
     __sys_path_tmp = sys.path ; sys.path.insert(0,funcrepr["__userFunction__path"])
     __module = __import__(funcrepr["__userFunction__modl"], globals(), locals(), [])
     __fonction = getattr(__module,funcrepr["__userFunction__name"])
     sys.path = __sys_path_tmp ; del __sys_path_tmp
-    __HX  = __fonction( __X )
+    if isinstance(xArgs, dict):
+        __HX  = __fonction( __X, **xArgs )
+    else:
+        __HX  = __fonction( __X )
     return numpy.ravel( __HX )
 
 # ==============================================================================
@@ -62,6 +65,7 @@ class FDApproximation(object):
             centeredDF            = False,
             increment             = 0.01,
             dX                    = None,
+            extraArguments        = None,
             avoidingRedundancy    = True,
             toleranceInRedundancy = 1.e-18,
             lenghtOfRedundancy    = -1,
@@ -70,6 +74,7 @@ class FDApproximation(object):
             mfEnabled             = False,
             ):
         self.__name = str(name)
+        self.__extraArgs = extraArguments
         if mpEnabled:
             try:
                 import multiprocessing
@@ -114,7 +119,7 @@ class FDApproximation(object):
                 self.__userFunction__modl = os.path.basename(mod).replace('.pyc','').replace('.pyo','').replace('.py','')
                 self.__userFunction__path = os.path.dirname(mod)
                 del mod
-                self.__userOperator = Operator( name = self.__name, fromMethod = Function, avoidingRedundancy = self.__avoidRC, inputAsMultiFunction = self.__mfEnabled )
+                self.__userOperator = Operator( name = self.__name, fromMethod = Function, avoidingRedundancy = self.__avoidRC, inputAsMultiFunction = self.__mfEnabled, extraArguments = self.__extraArgs )
                 self.__userFunction = self.__userOperator.appliedTo # Pour le calcul Direct
             elif isinstance(Function,types.MethodType):
                 logging.debug("FDA Calculs en multiprocessing : MethodType")
@@ -128,12 +133,12 @@ class FDApproximation(object):
                 self.__userFunction__modl = os.path.basename(mod).replace('.pyc','').replace('.pyo','').replace('.py','')
                 self.__userFunction__path = os.path.dirname(mod)
                 del mod
-                self.__userOperator = Operator( name = self.__name, fromMethod = Function, avoidingRedundancy = self.__avoidRC, inputAsMultiFunction = self.__mfEnabled )
+                self.__userOperator = Operator( name = self.__name, fromMethod = Function, avoidingRedundancy = self.__avoidRC, inputAsMultiFunction = self.__mfEnabled, extraArguments = self.__extraArgs )
                 self.__userFunction = self.__userOperator.appliedTo # Pour le calcul Direct
             else:
                 raise TypeError("User defined function or method has to be provided for finite differences approximation.")
         else:
-            self.__userOperator = Operator( name = self.__name, fromMethod = Function, avoidingRedundancy = self.__avoidRC, inputAsMultiFunction = self.__mfEnabled )
+            self.__userOperator = Operator( name = self.__name, fromMethod = Function, avoidingRedundancy = self.__avoidRC, inputAsMultiFunction = self.__mfEnabled, extraArguments = self.__extraArgs )
             self.__userFunction = self.__userOperator.appliedTo
         #
         self.__centeredDF = bool(centeredDF)
@@ -160,9 +165,12 @@ class FDApproximation(object):
         return __ac, __iac
 
     # ---------------------------------------------------------
-    def DirectOperator(self, X ):
+    def DirectOperator(self, X, **extraArgs ):
         """
         Calcul du direct à l'aide de la fonction fournie.
+
+        NB : les extraArgs sont là pour assurer la compatibilité d'appel, mais
+        ne doivent pas être données ici à la fonction utilisateur.
         """
         logging.debug("FDA Calcul DirectOperator (explicite)")
         if self.__mfEnabled:
@@ -249,8 +257,8 @@ class FDApproximation(object):
                         _X_moins_dXi    = numpy.array( _X.A1, dtype=float )
                         _X_moins_dXi[i] = _X[i] - _dXi
                         #
-                        _jobs.append( (_X_plus_dXi,  funcrepr) )
-                        _jobs.append( (_X_moins_dXi, funcrepr) )
+                        _jobs.append( (_X_plus_dXi,  self.__extraArgs, funcrepr) )
+                        _jobs.append( (_X_moins_dXi, self.__extraArgs, funcrepr) )
                     #
                     import multiprocessing
                     self.__pool = multiprocessing.Pool(self.__mpWorkers)
@@ -303,12 +311,12 @@ class FDApproximation(object):
                         "__userFunction__name" : self.__userFunction__name,
                     }
                     _jobs = []
-                    _jobs.append( (_X.A1, funcrepr) )
+                    _jobs.append( (_X.A1, self.__extraArgs, funcrepr) )
                     for i in range( len(_dX) ):
                         _X_plus_dXi    = numpy.array( _X.A1, dtype=float )
                         _X_plus_dXi[i] = _X[i] + _dX[i]
                         #
-                        _jobs.append( (_X_plus_dXi, funcrepr) )
+                        _jobs.append( (_X_plus_dXi, self.__extraArgs, funcrepr) )
                     #
                     import multiprocessing
                     self.__pool = multiprocessing.Pool(self.__mpWorkers)
@@ -372,9 +380,12 @@ class FDApproximation(object):
         return _Jacobienne
 
     # ---------------------------------------------------------
-    def TangentOperator(self, paire ):
+    def TangentOperator(self, paire, **extraArgs ):
         """
         Calcul du tangent à l'aide de la Jacobienne.
+
+        NB : les extraArgs sont là pour assurer la compatibilité d'appel, mais
+        ne doivent pas être données ici à la fonction utilisateur.
         """
         if self.__mfEnabled:
             assert len(paire) == 1, "Incorrect lenght of arguments"
@@ -401,9 +412,12 @@ class FDApproximation(object):
             else:                return _HtX.A1
 
     # ---------------------------------------------------------
-    def AdjointOperator(self, paire ):
+    def AdjointOperator(self, paire, **extraArgs ):
         """
         Calcul de l'adjoint à l'aide de la Jacobienne.
+
+        NB : les extraArgs sont là pour assurer la compatibilité d'appel, mais
+        ne doivent pas être données ici à la fonction utilisateur.
         """
         if self.__mfEnabled:
             assert len(paire) == 1, "Incorrect lenght of arguments"
@@ -429,84 +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"
@@ -532,14 +468,14 @@ def EnsembleOfBackgroundPerturbations( _bgcenter, _bgcovariance, _nbmembers, _wi
         notes manuscrites de MB et conforme au code de PS avec eps = -1
         """
         eps = -1
-        Q = numpy.eye(N-1)-numpy.ones((N-1,N-1))/numpy.sqrt(N)/(numpy.sqrt(N)-eps)
+        Q = numpy.identity(N-1)-numpy.ones((N-1,N-1))/numpy.sqrt(N)/(numpy.sqrt(N)-eps)
         Q = numpy.concatenate((Q, [eps*numpy.ones(N-1)/numpy.sqrt(N)]), axis=0)
         R, _ = numpy.linalg.qr(numpy.random.normal(size = (N-1,N-1)))
         Q = numpy.dot(Q,R)
         Zr = numpy.dot(Q,Zr)
         return Zr.T
     #
-    _bgcenter = numpy.ravel(_bgcenter)[:,None]
+    _bgcenter = numpy.ravel(_bgcenter).reshape((-1,1))
     if _nbmembers < 1:
         raise ValueError("Number of members has to be strictly more than 1 (given number: %s)."%(str(_nbmembers),))
     if _bgcovariance is None:
@@ -568,14 +504,29 @@ def EnsembleOfBackgroundPerturbations( _bgcenter, _bgcovariance, _nbmembers, _wi
     return BackgroundEnsemble
 
 # ==============================================================================
-def EnsembleOfAnomalies( _ensemble, _optmean = None):
+def EnsembleOfAnomalies( Ensemble, OptMean = None, Normalisation = 1.):
     "Renvoie les anomalies centrées à partir d'un ensemble TailleEtat*NbMembres"
-    if _optmean is None:
-        Em = numpy.asarray(_ensemble).mean(axis=1, dtype=mfp).astype('float')[:,numpy.newaxis]
+    if OptMean is None:
+        __Em = numpy.asarray(Ensemble).mean(axis=1, dtype=mfp).astype('float').reshape((-1,1))
     else:
-        Em = numpy.ravel(_optmean)[:,numpy.newaxis]
+        __Em = numpy.ravel(OptMean).reshape((-1,1))
+    #
+    return Normalisation * (numpy.asarray(Ensemble) - __Em)
+
+# ==============================================================================
+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
+    # Assure la positivité
+    __epsilon    = mpr*numpy.trace(__Covariance)
+    __Covariance = __Covariance + __epsilon * numpy.identity(__n)
     #
-    return numpy.asarray(_ensemble) - Em
+    return __Covariance
 
 # ==============================================================================
 def CovarianceInflation(
@@ -618,7 +569,7 @@ def CovarianceInflation(
         __n, __m = numpy.asarray(InputCovOrEns).shape
         if __n != __m:
             raise ValueError("Additive inflation can only be applied to squared (covariance) matrix.")
-        OutputCovOrEns = (1. - InflationFactor) * InputCovOrEns + InflationFactor * numpy.eye(__n)
+        OutputCovOrEns = (1. - InflationFactor) * InputCovOrEns + InflationFactor * numpy.identity(__n)
     #
     elif InflationType == "HybridOnBackgroundCovariance":
         if InflationFactor < 0.:
@@ -643,12 +594,151 @@ def CovarianceInflation(
     return OutputCovOrEns
 
 # ==============================================================================
-def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
+def enks(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="EnKS16-KalmanFilterFormula"):
+    """
+    EnKS
     """
-    Stochastic EnKF (Envensen 1994, Burgers 1998)
+    #
+    # Initialisations
+    # ---------------
+    #
+    # 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
+    #
+    # 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((__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 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
 
-    selfA est identique au "self" d'algorithme appelant et contient les
-    valeurs.
+# ==============================================================================
+def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
+    """
+    Ensemble-Transform EnKF
     """
     if selfA._parameters["EstimationOf"] == "Parameters":
         selfA._parameters["StoreInternalVariables"] = True
@@ -684,6 +774,10 @@ def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
         or selfA._toStore("APosterioriCovariance"):
         BI = B.getI()
         RI = R.getI()
+    elif VariantM != "KalmanFilterFormula":
+        RI = R.getI()
+    if VariantM == "KalmanFilterFormula":
+        RIdemi = R.sqrtmI()
     #
     # Initialisation
     # --------------
@@ -691,14 +785,13 @@ def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     __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( numpy.ravel(Xb) )
+        selfA.StoredVariables["Analysis"].store( Xb )
         if selfA._toStore("APosterioriCovariance"):
             selfA.StoredVariables["APosterioriCovariance"].store( Pn )
             covarianceXa = Pn
@@ -707,9 +800,9 @@ def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     #
     for step in range(duration-1):
         if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
         #
         if U is not None:
             if hasattr(U,"store") and len(U)>1:
@@ -747,53 +840,171 @@ def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
                 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))
+        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 == "KalmanFilterFormula05":
-            PfHT, HPfHT = 0., 0.
-            for i in range(__m):
-                Exfi = Xn_predicted[:,i].reshape((__n,-1)) - Xfm
-                Eyfi = HX_predicted[:,i].reshape((__p,-1)) - Hfm
-                PfHT  += Exfi * Eyfi.T
-                HPfHT += Eyfi * Eyfi.T
-            PfHT  = (1./(__m-1)) * PfHT
-            HPfHT = (1./(__m-1)) * HPfHT
-            Kn     = PfHT * ( R + HPfHT ).I
-            del PfHT, HPfHT
+        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
             #
-            for i in range(__m):
-                ri = numpy.random.multivariate_normal(numpy.zeros(__p), Rn)
-                Xn[:,i] = numpy.ravel(Xn_predicted[:,i]) + Kn @ (numpy.ravel(Ynpu) + ri - HX_predicted[:,i])
+            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 == "KalmanFilterFormula16":
-            EpY   = EnsembleOfCenteredPerturbations(Ynpu, Rn, __m)
-            EpYm  = EpY.mean(axis=1, dtype=mfp).astype('float').reshape((__p,-1))
+        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,
+                )
             #
-            EaX   = EnsembleOfAnomalies( Xn_predicted ) / numpy.sqrt(__m-1)
-            EaY = (HX_predicted - Hfm - EpY + EpYm) / numpy.sqrt(__m-1)
+            Hto = EaHX.T @ (RI * EaHX)
+            Htb = (__m-1) * numpy.identity(__m)
+            Hta = Hto + Htb
             #
-            Kn = EaX @ EaY.T @ numpy.linalg.inv( EaY @ EaY.T)
+            Pta = numpy.linalg.inv( Hta )
+            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
             #
-            for i in range(__m):
-                Xn[:,i] = numpy.ravel(Xn_predicted[:,i]) + Kn @ (numpy.ravel(EpY[:,i]) - HX_predicted[:,i])
+            Xn  = Xfm + EaX @ (vw[:,None] + EWa)
         #--------------------------
-        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"],
+        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,
                 )
-        #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,-1))
+            #
+            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)
         #--------------------------
-        #
-        if selfA._parameters["StoreInternalVariables"] \
-            or selfA._toStore("CostFunctionJ") \
-            or selfA._toStore("CostFunctionJb") \
+        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:
+            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") \
@@ -856,16 +1067,16 @@ def senkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
             if selfA._toStore("CostFunctionJAtCurrentOptimum"):
                 selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
         if selfA._toStore("APosterioriCovariance"):
-            Eai = EnsembleOfAnomalies( Xn ) / numpy.sqrt(__m-1) # Anomalies
-            Pn = Eai @ Eai.T
-            Pn = 0.5 * (Pn + Pn.T)
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            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 )
     #
     # Stockage final supplémentaire de l'optimum en estimation de paramètres
     # ----------------------------------------------------------------------
@@ -880,12 +1091,10 @@ 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 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):
     """
-    Ensemble-Transform EnKF (ETKF or Deterministic EnKF: Bishop 2001, Hunt 2007)
-
-    selfA est identique au "self" d'algorithme appelant et contient les
-    valeurs.
+    Iterative EnKF
     """
     if selfA._parameters["EstimationOf"] == "Parameters":
         selfA._parameters["StoreInternalVariables"] = True
@@ -920,11 +1129,7 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
         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.choleskyI()
+    RI = R.getI()
     #
     # Initialisation
     # --------------
@@ -936,10 +1141,10 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     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( numpy.ravel(Xb) )
+        selfA.StoredVariables["Analysis"].store( Xb )
         if selfA._toStore("APosterioriCovariance"):
             selfA.StoredVariables["APosterioriCovariance"].store( Pn )
             covarianceXa = Pn
@@ -948,9 +1153,9 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     #
     for step in range(duration-1):
         if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
         #
         if U is not None:
             if hasattr(U,"store") and len(U)>1:
@@ -968,175 +1173,61 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
                 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
-            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 )
-        EaHX  = numpy.array(HX_predicted - Hfm)
-        #
-        #--------------------------
-        if VariantM == "KalmanFilterFormula":
-            mS    = RIdemi * EaHX / numpy.sqrt(__m-1)
-            delta = RIdemi * ( Ynpu - Hfm )
-            mT    = numpy.linalg.inv( numpy.eye(__m) + mS.T @ mS )
-            vw    = mT @ mS.transpose() @ delta
-            #
-            Tdemi = numpy.real(scipy.linalg.sqrtm(mT))
-            mU    = numpy.eye(__m)
-            #
-            EaX   = EaX / numpy.sqrt(__m-1)
-            Xn    = Xfm + EaX @ ( vw.reshape((__m,-1)) + numpy.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.eye(__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.eye(__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.eye(__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,
-                )
+        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
             #
-            Hto = EaHX.T @ (RI * EaHX)
-            Htb = ((__m+1) / (__m-1)) * \
-                ( (1 + 1/__m + vw.T @ vw / (__m-1)) * numpy.eye(__m) - 2 * vw @ vw.T / (__m-1) ) \
-                / (1 + 1/__m + vw.T @ vw / (__m-1))**2
-            Hta = Hto + Htb
+            A2 = EnsembleOfAnomalies( E2 )
             #
-            Pta = numpy.linalg.inv( Hta )
-            EWa = numpy.real(scipy.linalg.sqrtm((__m-1)*Pta)) # Partie imaginaire ~= 10^-18
+            if BnotT:
+                Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
+                A2 = math.sqrt(__m-1) * A2 @ Ta / _epsilon
             #
-            Xn  = Xfm + EaX @ (vw[:,None] + EWa)
+            Xn = vx2 + A2
         #--------------------------
         else:
             raise ValueError("VariantM has to be chosen in the authorized methods list.")
@@ -1147,7 +1238,7 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
                 selfA._parameters["InflationFactor"],
                 )
         #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,-1))
+        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
         #--------------------------
         #
         if selfA._parameters["StoreInternalVariables"] \
@@ -1173,14 +1264,14 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
             or selfA._toStore("CurrentState"):
             selfA.StoredVariables["CurrentState"].store( Xn )
         if selfA._toStore("ForecastState"):
-            selfA.StoredVariables["ForecastState"].store( EMX )
+            selfA.StoredVariables["ForecastState"].store( E2 )
         if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( EMX - Xa.reshape((__n,1)) )
+            selfA.StoredVariables["BMA"].store( E2 - Xa )
         if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( - HX_predicted + Ynpu.reshape((__p,1)) )
+            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu )
         if selfA._toStore("SimulatedObservationAtCurrentState") \
             or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HX_predicted )
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
         # ---> autres
         if selfA._parameters["StoreInternalVariables"] \
             or selfA._toStore("CostFunctionJ") \
@@ -1215,10 +1306,7 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
             if selfA._toStore("CostFunctionJAtCurrentOptimum"):
                 selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
         if selfA._toStore("APosterioriCovariance"):
-            Eai = EnsembleOfAnomalies( Xn ) / numpy.sqrt(__m-1) # Anomalies
-            Pn = Eai @ Eai.T
-            Pn = 0.5 * (Pn + Pn.T)
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
         if selfA._parameters["EstimationOf"] == "Parameters" \
             and J < previousJMinimum:
             previousJMinimum    = J
@@ -1238,14 +1326,297 @@ def etkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="KalmanFilterFormula"):
     #
     return 0
 
+# ==============================================================================
+def incr3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+    """
+    3DVAR incrémental
+    """
+    #
+    # Initialisations
+    # ---------------
+    #
+    # Opérateur non-linéaire pour la boucle externe
+    Hm = HO["Direct"].appliedTo
+    #
+    # Précalcul des inversions de B et R
+    BI = B.getI()
+    RI = R.getI()
+    #
+    # Point de démarrage de l'optimisation
+    Xini = selfA._parameters["InitializationPoint"]
+    #
+    HXb = numpy.asmatrix(numpy.ravel( Hm( Xb ) )).T
+    Innovation = Y - HXb
+    #
+    # Outer Loop
+    # ----------
+    iOuter = 0
+    J      = 1./mpr
+    DeltaJ = 1./mpr
+    Xr     = Xini.reshape((-1,1))
+    while abs(DeltaJ) >= selfA._parameters["CostDecrementTolerance"] and iOuter <= selfA._parameters["MaximumNumberOfSteps"]:
+        #
+        # Inner Loop
+        # ----------
+        Ht = HO["Tangent"].asMatrix(Xr)
+        Ht = Ht.reshape(Y.size,Xr.size) # ADAO & check shape
+        #
+        # Définition de la fonction-coût
+        # ------------------------------
+        def CostFunction(dx):
+            _dX  = numpy.asmatrix(numpy.ravel( dx )).T
+            if selfA._parameters["StoreInternalVariables"] or \
+                selfA._toStore("CurrentState") or \
+                selfA._toStore("CurrentOptimum"):
+                selfA.StoredVariables["CurrentState"].store( Xb + _dX )
+            _HdX = Ht * _dX
+            _HdX = numpy.asmatrix(numpy.ravel( _HdX )).T
+            _dInnovation = Innovation - _HdX
+            if selfA._toStore("SimulatedObservationAtCurrentState") or \
+                selfA._toStore("SimulatedObservationAtCurrentOptimum"):
+                selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HXb + _HdX )
+            if selfA._toStore("InnovationAtCurrentState"):
+                selfA.StoredVariables["InnovationAtCurrentState"].store( _dInnovation )
+            #
+            Jb  = float( 0.5 * _dX.T * BI * _dX )
+            Jo  = float( 0.5 * _dInnovation.T * RI * _dInnovation )
+            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(dx):
+            _dX          = numpy.asmatrix(numpy.ravel( dx )).T
+            _HdX         = Ht * _dX
+            _HdX         = numpy.asmatrix(numpy.ravel( _HdX )).T
+            _dInnovation = Innovation - _HdX
+            GradJb       = BI * _dX
+            GradJo       = - Ht.T @ (RI * _dInnovation)
+            GradJ        = numpy.ravel( GradJb ) + numpy.ravel( GradJo )
+            return GradJ
+        #
+        # Minimisation de la fonctionnelle
+        # --------------------------------
+        nbPreviousSteps = selfA.StoredVariables["CostFunctionJ"].stepnumber()
+        #
+        if selfA._parameters["Minimizer"] == "LBFGSB":
+            # Minimum, J_optimal, Informations = scipy.optimize.fmin_l_bfgs_b(
+            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          = numpy.zeros(Xini.size),
+                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          = numpy.zeros(Xini.size),
+                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          = numpy.zeros(Xini.size),
+                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          = numpy.zeros(Xini.size),
+                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          = numpy.zeros(Xini.size),
+                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]
+        #
+        if selfA._parameters["StoreInternalVariables"] or selfA._toStore("CurrentState"):
+            Minimum = selfA.StoredVariables["CurrentState"][IndexMin]
+            Minimum = numpy.asmatrix(numpy.ravel( Minimum )).T
+        else:
+            Minimum = Xb + numpy.asmatrix(numpy.ravel( Minimum )).T
+        #
+        Xr     = Minimum
+        DeltaJ = selfA.StoredVariables["CostFunctionJ" ][-1] - J
+        iOuter = selfA.StoredVariables["CurrentIterationNumber"][-1]
+    #
+    # Obtention de l'analyse
+    # ----------------------
+    Xa = Xr
+    #
+    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):
     """
-    Maximum Likelihood Ensemble Filter (EnKF/MLEF Zupanski 2005, Bocquet 2013)
-
-    selfA est identique au "self" d'algorithme appelant et contient les
-    valeurs.
+    Maximum Likelihood Ensemble Filter
     """
     if selfA._parameters["EstimationOf"] == "Parameters":
         selfA._parameters["StoreInternalVariables"] = True
@@ -1295,7 +1666,7 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
     Xn = EnsembleOfBackgroundPerturbations( Xb, None, __m )
     #
     if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
-        selfA.StoredVariables["Analysis"].store( numpy.ravel(Xb) )
+        selfA.StoredVariables["Analysis"].store( Xb )
         if selfA._toStore("APosterioriCovariance"):
             selfA.StoredVariables["APosterioriCovariance"].store( Pn )
             covarianceXa = Pn
@@ -1304,9 +1675,9 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
     #
     for step in range(duration-1):
         if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
         #
         if U is not None:
             if hasattr(U,"store") and len(U)>1:
@@ -1340,33 +1711,33 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
         #--------------------------
         if VariantM == "MLEF13":
             Xfm = numpy.ravel(Xn_predicted.mean(axis=1, dtype=mfp).astype('float'))
-            EaX = EnsembleOfAnomalies( Xn_predicted ) / numpy.sqrt(__m-1)
-            Ua  = numpy.eye(__m)
+            EaX = EnsembleOfAnomalies( Xn_predicted, Xfm, 1./math.sqrt(__m-1) )
+            Ua  = numpy.identity(__m)
             __j = 0
             Deltaw = 1
             if not BnotT:
-                Ta  = numpy.eye(__m)
+                Ta  = numpy.identity(__m)
             vw  = numpy.zeros(__m)
             while numpy.linalg.norm(Deltaw) >= _e and __j <= _jmax:
-                vx1 = (Xfm + EaX @ vw).reshape((__n,-1))
+                vx1 = (Xfm + EaX @ vw).reshape((__n,1))
                 #
                 if BnotT:
                     E1 = vx1 + _epsilon * EaX
                 else:
-                    E1 = vx1 + numpy.sqrt(__m-1) * EaX @ Ta
+                    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))
+                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) ) / numpy.sqrt(__m-1)
+                    EaY = ( (HE2 - vy2) @ numpy.linalg.inv(Ta) ) / math.sqrt(__m-1)
                 #
                 GradJ = numpy.ravel(vw[:,None] - EaY.transpose() @ (RI * ( Ynpu - vy2 )))
-                mH = numpy.eye(__m) + EaY.transpose() @ (RI * EaY)
+                mH = numpy.identity(__m) + EaY.transpose() @ (RI * EaY)
                 Deltaw = - numpy.linalg.solve(mH,GradJ)
                 #
                 vw = vw + Deltaw
@@ -1379,7 +1750,7 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
             if BnotT:
                 Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
             #
-            Xn = vx1 + numpy.sqrt(__m-1) * EaX @ Ta @ Ua
+            Xn = vx1 + math.sqrt(__m-1) * EaX @ Ta @ Ua
         #--------------------------
         else:
             raise ValueError("VariantM has to be chosen in the authorized methods list.")
@@ -1390,7 +1761,7 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
                 selfA._parameters["InflationFactor"],
                 )
         #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,-1))
+        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
         #--------------------------
         #
         if selfA._parameters["StoreInternalVariables"] \
@@ -1418,9 +1789,9 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
         if selfA._toStore("ForecastState"):
             selfA.StoredVariables["ForecastState"].store( EMX )
         if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( EMX - Xa.reshape((__n,1)) )
+            selfA.StoredVariables["BMA"].store( EMX - Xa )
         if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu.reshape((__p,-1)) )
+            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu )
         if selfA._toStore("SimulatedObservationAtCurrentState") \
             or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
             selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
@@ -1458,10 +1829,7 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
             if selfA._toStore("CostFunctionJAtCurrentOptimum"):
                 selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
         if selfA._toStore("APosterioriCovariance"):
-            Eai = EnsembleOfAnomalies( Xn ) / numpy.sqrt(__m-1) # Anomalies
-            Pn = Eai @ Eai.T
-            Pn = 0.5 * (Pn + Pn.T)
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
         if selfA._parameters["EstimationOf"] == "Parameters" \
             and J < previousJMinimum:
             previousJMinimum    = J
@@ -1482,13 +1850,416 @@ def mlef(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="MLEF13",
     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 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 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 )
+    #
+    if hasattr(Y,"stepnumber"):
+        duration = Y.stepnumber()
+    else:
+        duration = 2
+    #
+    # 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
     """
-    Iterative EnKF (Sakov 2012, Sakov 2018)
+    #
+    # 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 = 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()
+    #
+    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]
+        Minimum = numpy.asmatrix(numpy.ravel( Minimum )).T
+    else:
+        Minimum = Xb + BHT * 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:
+            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
+            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
 
-    selfA est identique au "self" d'algorithme appelant et contient les
-    valeurs.
+# ==============================================================================
+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
@@ -1523,7 +2294,7 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
         or selfA._toStore("CurrentOptimum") \
         or selfA._toStore("APosterioriCovariance"):
         BI = B.getI()
-    RI = R.getI()
+        RI = R.getI()
     #
     # Initialisation
     # --------------
@@ -1535,10 +2306,10 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
     else:                         Rn = R
     if hasattr(Q,"asfullmatrix"): Qn = Q.asfullmatrix(__n)
     else:                         Qn = Q
-    Xn = EnsembleOfBackgroundPerturbations( Xb, Pn, __m )
+    Xn = EnsembleOfBackgroundPerturbations( Xb, None, __m )
     #
     if len(selfA.StoredVariables["Analysis"])==0 or not selfA._parameters["nextStep"]:
-        selfA.StoredVariables["Analysis"].store( numpy.ravel(Xb) )
+        selfA.StoredVariables["Analysis"].store( Xb )
         if selfA._toStore("APosterioriCovariance"):
             selfA.StoredVariables["APosterioriCovariance"].store( Pn )
             covarianceXa = Pn
@@ -1547,9 +2318,9 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
     #
     for step in range(duration-1):
         if hasattr(Y,"store"):
-            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y[step+1] ).reshape((__p,1))
         else:
-            Ynpu = numpy.ravel( Y ).reshape((__p,-1))
+            Ynpu = numpy.ravel( Y ).reshape((__p,1))
         #
         if U is not None:
             if hasattr(U,"store") and len(U)>1:
@@ -1567,61 +2338,57 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
                 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
+            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))
+        #
         #--------------------------
-        if VariantM == "IEnKF12":
-            Xfm = numpy.ravel(Xn.mean(axis=1, dtype=mfp).astype('float'))
-            EaX = EnsembleOfAnomalies( Xn ) / numpy.sqrt(__m-1)
-            __j = 0
-            Deltaw = 1
-            if not BnotT:
-                Ta  = numpy.eye(__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 + numpy.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) ) / numpy.sqrt(__m-1)
-                #
-                GradJ = numpy.ravel(vw[:,None] - EaY.transpose() @ (RI * ( Ynpu - vy1 )))
-                mH = numpy.eye(__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 VariantM == "KalmanFilterFormula05":
+            PfHT, HPfHT = 0., 0.
+            for i in range(__m):
+                Exfi = Xn_predicted[:,i].reshape((__n,1)) - Xfm
+                Eyfi = HX_predicted[:,i].reshape((__p,1)) - Hfm
+                PfHT  += Exfi * Eyfi.T
+                HPfHT += Eyfi * Eyfi.T
+            PfHT  = (1./(__m-1)) * PfHT
+            HPfHT = (1./(__m-1)) * HPfHT
+            Kn     = PfHT * ( R + HPfHT ).I
+            del PfHT, HPfHT
             #
-            A2 = EnsembleOfAnomalies( E2 )
+            for i in range(__m):
+                ri = numpy.random.multivariate_normal(numpy.zeros(__p), Rn)
+                Xn[:,i] = numpy.ravel(Xn_predicted[:,i]) + Kn @ (numpy.ravel(Ynpu) + ri - HX_predicted[:,i])
+        #--------------------------
+        elif VariantM == "KalmanFilterFormula16":
+            EpY   = EnsembleOfCenteredPerturbations(Ynpu, Rn, __m)
+            EpYm  = EpY.mean(axis=1, dtype=mfp).astype('float').reshape((__p,1))
             #
-            if BnotT:
-                Ta = numpy.real(scipy.linalg.sqrtm(numpy.linalg.inv( mH )))
-                A2 = numpy.sqrt(__m-1) * A2 @ Ta / _epsilon
+            EaX   = EnsembleOfAnomalies( Xn_predicted ) / math.sqrt(__m-1)
+            EaY = (HX_predicted - Hfm - EpY + EpYm) / math.sqrt(__m-1)
             #
-            Xn = vx2 + A2
+            Kn = EaX @ EaY.T @ numpy.linalg.inv( EaY @ EaY.T)
+            #
+            for i in range(__m):
+                Xn[:,i] = numpy.ravel(Xn_predicted[:,i]) + Kn @ (numpy.ravel(EpY[:,i]) - HX_predicted[:,i])
         #--------------------------
         else:
             raise ValueError("VariantM has to be chosen in the authorized methods list.")
@@ -1632,7 +2399,7 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
                 selfA._parameters["InflationFactor"],
                 )
         #
-        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,-1))
+        Xa = Xn.mean(axis=1, dtype=mfp).astype('float').reshape((__n,1))
         #--------------------------
         #
         if selfA._parameters["StoreInternalVariables"] \
@@ -1658,14 +2425,14 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
             or selfA._toStore("CurrentState"):
             selfA.StoredVariables["CurrentState"].store( Xn )
         if selfA._toStore("ForecastState"):
-            selfA.StoredVariables["ForecastState"].store( E2 )
+            selfA.StoredVariables["ForecastState"].store( EMX )
         if selfA._toStore("BMA"):
-            selfA.StoredVariables["BMA"].store( E2 - Xa )
+            selfA.StoredVariables["BMA"].store( EMX - Xa )
         if selfA._toStore("InnovationAtCurrentState"):
-            selfA.StoredVariables["InnovationAtCurrentState"].store( - HE2 + Ynpu.reshape((__p,-1)) )
+            selfA.StoredVariables["InnovationAtCurrentState"].store( - HX_predicted + Ynpu )
         if selfA._toStore("SimulatedObservationAtCurrentState") \
             or selfA._toStore("SimulatedObservationAtCurrentOptimum"):
-            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HE2 )
+            selfA.StoredVariables["SimulatedObservationAtCurrentState"].store( HX_predicted )
         # ---> autres
         if selfA._parameters["StoreInternalVariables"] \
             or selfA._toStore("CostFunctionJ") \
@@ -1700,10 +2467,7 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
             if selfA._toStore("CostFunctionJAtCurrentOptimum"):
                 selfA.StoredVariables["CostFunctionJAtCurrentOptimum" ].store( selfA.StoredVariables["CostFunctionJ" ][IndexMin] )
         if selfA._toStore("APosterioriCovariance"):
-            Eai = EnsembleOfAnomalies( Xn ) / numpy.sqrt(__m-1) # Anomalies
-            Pn = Eai @ Eai.T
-            Pn = 0.5 * (Pn + Pn.T)
-            selfA.StoredVariables["APosterioriCovariance"].store( Pn )
+            selfA.StoredVariables["APosterioriCovariance"].store( EnsembleErrorCovariance(Xn) )
         if selfA._parameters["EstimationOf"] == "Parameters" \
             and J < previousJMinimum:
             previousJMinimum    = J
@@ -1723,6 +2487,790 @@ def ienkf(selfA, Xb, Y, U, HO, EM, CM, R, B, Q, VariantM="IEnKF12",
     #
     return 0
 
+# ==============================================================================
+def std3dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+    """
+    3DVAR
+    """
+    #
+    # Initialisations
+    # ---------------
+    #
+    # Opérateurs
+    Hm = HO["Direct"].appliedTo
+    Ha = HO["Adjoint"].appliedInXTo
+    #
+    # 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 )
+    #
+    # Précalcul des inversions de B et R
+    BI = B.getI()
+    RI = R.getI()
+    #
+    # Point de démarrage de l'optimisation
+    Xini = selfA._parameters["InitializationPoint"]
+    #
+    # 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
+    #
+    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 std4dvar(selfA, Xb, Y, U, HO, EM, CM, R, B, Q):
+    """
+    4DVAR
+    """
+    #
+    # Initialisations
+    # ---------------
+    #
+    # 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()
+    else:
+        duration = 2
+    #
+    # Précalcul des inversions de B et R
+    BI = B.getI()
+    RI = R.getI()
+    #
+    # 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
+    #
+    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
+    #
+    # 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
+    #
+    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 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 )
+        #
+        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
+    #
+    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
+        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]
+        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:
+            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()
+        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
+
 # ==============================================================================
 if __name__ == "__main__":
     print('\n AUTODIAGNOSTIC\n')