#820 Assemble of SolidDeltaResidual runs correctly (but does not yet compute...

#820 Assemble of SolidDeltaResidual runs correctly (but does not yet compute what is intended: it's still the content from SecondPiolaKirchhoffStressTensor...). There is currently a factor 2. discrepancy with same quantity computed for dev purpose in Freefem.

Sources/ModelInstances/UnderDevelopment/Poromechanics/ImplicitStepFluid/InnerLoop/VariationalFormulation.hxx

@@ -367,7 +367,19 @@ namespace HappyHeart
                         GlobalVectorWithCoefficient with_coeff(delta_residual, 1.);
                         GetSolidDeltaResidualOperator().Assemble(std::make_tuple(std::ref(with_coeff)),
                                                                  this->GetVariableHolder().GetMidpointPosition());
+
+                        const auto filename = parent::GetOutputDirectory(numbering_subset)
+                        + "/"
+                        + DifferentialPreffix(differential::yes)
+                        + "delta_residual_" + GetIterationTag() + ".m";
+                        
+                        delta_residual.View(parent::MpiHappyHeart(),
+                                               filename,
+                                               __FILE__, __LINE__,
+                                               PETSC_VIEWER_ASCII_MATLAB);
+                        
                     }
+
                     
 
                     // \todo #820 At the moment, I accept my norm is not the same as Bruno's; see what Petsc gives when