.. index:: single: AdjointTest
.. index:: single: FunctionTest
.. index:: single: GradientTest
+.. index:: single: LinearityTest
.. index:: single: AlgorithmParameters
.. index:: single: AmplitudeOfInitialDirection
1000. By default, the seed is left uninitialized, and so use the default
initialization from the computer.
+**"LinearityTest"**
+
+ *Required commands*
+ *"CheckingPoint",
+ "ObservationOperator"*
+
+ AmplitudeOfInitialDirection
+ This key indicates the scaling of the initial perturbation build as a vector
+ used for the directional derivative around the nominal checking point. The
+ default is 1, that means no scaling.
+
+ EpsilonMinimumExponent
+ This key indicates the minimal exponent value of the power of 10 coefficient
+ to be used to decrease the increment multiplier. The default is -8, and it
+ has to be between 0 and -20. For example, its default value leads to
+ calculate the residue of the scalar product formula with a fixed increment
+ multiplied from 1.e0 to 1.e-8.
+
+ InitialDirection
+ This key indicates the vector direction used for the directional derivative
+ around the nominal checking point. It has to be a vector. If not specified,
+ this direction defaults to a random perturbation around zero of the same
+ vector size than the checking point.
+
+ ResiduFormula
+ This key indicates the residue formula that has to be used for the test. The
+ default choice is "CenteredDL", and the possible ones are "CenteredDL"
+ (residue of the difference between the function at nominal point and the
+ values with positive and negative increments, which has to stay very small),
+ "Taylor" (residue of the Taylor development of the operator normalized by
+ the nominal value, which has to stay very small), "NominalTaylor" (residue
+ of the order 1 approximations of the operator, normalized to the nominal
+ point, which has to stay close to 1), and "NominalTaylorRMS" (residue of the
+ order 1 approximations of the operator, normalized by RMS to the nominal
+ point, which has to stay close to 0).
+
+ SetSeed
+ This key allow to give an integer in order to fix the seed of the random
+ generator used to generate the ensemble. A convenient value is for example
+ 1000. By default, the seed is left uninitialized, and so use the default
+ initialization from the computer.
+
Requirements for functions describing an operator
-------------------------------------------------