void NeoHookeanMaterialNonLinear<Mesh>::computeStiffness ( const vector_Type&       sol,
                                                           Real                     /*factor*/,
                                                           const dataPtr_Type&      dataMaterial,
                                                           const mapMarkerVolumesPtr_Type mapsMarkerVolumes,
                                                           const displayerPtr_Type& displayer )
{
    this->M_stiff.reset (new vector_Type (*this->M_localMap) );

    displayer->leaderPrint (" \n******************************************************************\n  ");
    displayer->leaderPrint (" Non-Linear S-  Computing the Neo-Hookean nonlinear stiffness vector"     );
    displayer->leaderPrint (" \n******************************************************************\n  ");

    UInt totalDof   = this->M_FESpace->dof().numTotalDof();
    UInt dim        = this->M_FESpace->dim();

    VectorElemental dk_loc ( this->M_FESpace->fe().nbFEDof(), nDimensions );
    //vector_Type disp(sol);

    vector_Type dRep (sol, Repeated);

    mapIterator_Type it;

    for ( it = (*mapsMarkerVolumes).begin(); it != (*mapsMarkerVolumes).end(); it++ )
    {

        //Given the marker pointed by the iterator, let's extract the material parameters
        UInt marker = it->first;

        Real mu     = dataMaterial->mu (marker);
        Real bulk   = dataMaterial->bulk (marker);

        for ( UInt j (0); j < it->second.size(); j++ )
        {
            this->M_FESpace->fe().updateFirstDerivQuadPt ( * (it->second[j]) );

            UInt eleID = this->M_FESpace->fe().currentLocalId();

            for ( UInt iNode = 0 ; iNode < ( UInt ) this->M_FESpace->fe().nbFEDof() ; iNode++ )
            {
                UInt  iloc = this->M_FESpace->fe().patternFirst ( iNode );

                for ( UInt iComp = 0; iComp < nDimensions; ++iComp )
                {
                    UInt ig = this->M_FESpace->dof().localToGlobalMap ( eleID, iloc ) + iComp * dim + this->M_offset;
                    dk_loc[ iloc + iComp * this->M_FESpace->fe().nbFEDof() ] = dRep[ig];
                }
            }

            this->M_elvecK->zero();

            computeKinematicsVariables ( dk_loc );

            //! Stiffness for non-linear terms of the Neo-Hookean model
            /*!
              The results of the integrals are stored at each step into elvecK, until to build K matrix of the bilinear form
            */
            //! Volumetric part
            /*!
              Source term Pvol: int { bulk /2* (J1^2 - J1  + log(J1) ) * 1/J1 * (CofF1 : \nabla v) }
            */
            AssemblyElementalStructure::source_Pvol ( 0.5 * bulk, (*M_CofFk), (*M_Jack),
                                                      *this->M_elvecK,  this->M_FESpace->fe() );

            //! Isochoric part
            /*!
              Source term P1iso_NH
            */
            AssemblyElementalStructure::source_P1iso_NH ( mu, (*M_CofFk) , (*M_Fk),  (*M_Jack),  (*M_trCisok) ,
                                                          *this->M_elvecK,  this->M_FESpace->fe() );

            for ( UInt ic = 0; ic < nDimensions; ++ic )
            {
                /*!
                  M_elvecK is assemble into *vec_stiff vector that is recall
                  from updateSystem(matrix_ptrtype& mat_stiff, vector_ptr_type& vec_stiff)
                */
                assembleVector ( *this->M_stiff,
                                 *this->M_elvecK,
                                 this->M_FESpace->fe(),
                                 this->M_FESpace->dof(),
                                 ic, this->M_offset +  ic * totalDof );
            }
        }
    }

    this->M_stiff->globalAssemble();
}
void NeoHookeanMaterialNonLinear<Mesh>::updateNonLinearJacobianTerms ( matrixPtr_Type&       jacobian,
                                                                       const vector_Type&    disp,
                                                                       const dataPtr_Type&   dataMaterial,
                                                                       const mapMarkerVolumesPtr_Type mapsMarkerVolumes,
                                                                       const displayerPtr_Type&  displayer )
{
    displayer->leaderPrint ("   Non-Linear S-  updating non linear terms in the Jacobian Matrix (Neo-Hookean)");

    UInt totalDof = this->M_FESpace->dof().numTotalDof();
    VectorElemental dk_loc (this->M_FESpace->fe().nbFEDof(), nDimensions);

    vector_Type dRep (disp, Repeated);

    //! Number of displacement components
    UInt nc = nDimensions;

    //! Nonlinear part of jacobian
    //! loop on volumes: assembling source term

    mapIterator_Type it;

    for ( it = (*mapsMarkerVolumes).begin(); it != (*mapsMarkerVolumes).end(); it++ )
    {

        //Given the marker pointed by the iterator, let's extract the material parameters
        UInt marker = it->first;

        Real mu     = dataMaterial->mu (marker);
        Real bulk   = dataMaterial->bulk (marker);

        for ( UInt j (0); j < it->second.size(); j++ )
        {
            this->M_FESpace->fe().updateFirstDerivQuadPt ( * (it->second[j]) );

            UInt eleID = this->M_FESpace->fe().currentLocalId();

            for ( UInt iNode = 0; iNode < ( UInt ) this->M_FESpace->fe().nbFEDof(); iNode++ )
            {
                UInt  iloc = this->M_FESpace->fe().patternFirst ( iNode );

                for ( UInt iComp = 0; iComp < nDimensions; ++iComp )
                {
                    UInt ig = this->M_FESpace->dof().localToGlobalMap ( eleID, iloc ) + iComp * this->M_FESpace->dim() + this->M_offset;
                    dk_loc[iloc + iComp * this->M_FESpace->fe().nbFEDof()] = dRep[ig];
                }
            }

            this->M_elmatK->zero();

            //! Computes F, Cof(F), J = det(F), Tr(C)
            computeKinematicsVariables ( dk_loc );

            //! Stiffness for non-linear terms of the Neo-Hookean model
            /*!
              The results of the integrals are stored at each step into elmatK, until to build K matrix of the bilinear form
            */

            //! VOLUMETRIC PART
            //! 1. Stiffness matrix: int { 1/2 * bulk * ( 2 - 1/J + 1/J^2 ) * ( CofF : \nabla \delta ) (CofF : \nabla v) }
            AssemblyElementalStructure::stiff_Jac_Pvol_1term ( 0.5 * bulk, (*M_CofFk), (*M_Jack),
                                                               *this->M_elmatK, this->M_FESpace->fe() );

            //! 2. Stiffness matrix: int { 1/2 * bulk * ( 1/J- 1 - log(J)/J^2 ) * ( CofF [\nabla \delta]^t CofF ) : \nabla v }
            AssemblyElementalStructure::stiff_Jac_Pvol_2term ( 0.5 * bulk, (*M_CofFk), (*M_Jack),
                                                               *this->M_elmatK, this->M_FESpace->fe() );

            //! ISOCHORIC PART
            //! 1. Stiffness matrix : int { -2/3 * mu * J^(-5/3) *( CofF : \nabla \delta ) ( F : \nabla \v ) }
            AssemblyElementalStructure::stiff_Jac_P1iso_NH_1term ( (-2.0 / 3.0) * mu, (*M_CofFk), (*M_Fk), (*M_Jack),
                                                                   *this->M_elmatK, this->M_FESpace->fe() );

            //! 2. Stiffness matrix : int { 2/9 * mu * ( Ic_iso / J^2 )( CofF : \nabla \delta ) ( CofF : \nabla \v ) }
            AssemblyElementalStructure::stiff_Jac_P1iso_NH_2term ( (2.0 / 9.0) * mu, (*M_CofFk), (*M_Jack), (*M_trCisok),
                                                                   *this->M_elmatK, this->M_FESpace->fe() );

            //! 3. Stiffness matrix : int { mu * J^(-2/3) (\nabla \delta : \nabla \v)}
            AssemblyElementalStructure::stiff_Jac_P1iso_NH_3term ( mu, (*M_Jack), *this->M_elmatK, this->M_FESpace->fe() );

            //! 4. Stiffness matrix : int { -2/3 * mu * J^(-5/3) ( F : \nabla \delta ) ( CofF : \nabla \v ) }
            AssemblyElementalStructure::stiff_Jac_P1iso_NH_4term ( (-2.0 / 3.0) * mu, (*M_CofFk), (*M_Fk), (*M_Jack),
                                                                   *this->M_elmatK, this->M_FESpace->fe() );

            //! 5. Stiffness matrix : int { 1/3 * mu * J^(-2) * Ic_iso * (CofF [\nabla \delta]^t CofF ) : \nabla \v }
            AssemblyElementalStructure::stiff_Jac_P1iso_NH_5term ( (1.0 / 3.0) * mu, (*M_CofFk), (*M_Jack), (*M_trCisok),
                                                                   *this->M_elmatK, this->M_FESpace->fe() );

            //! assembling
            for ( UInt ic = 0; ic < nc; ++ic )
            {
                for ( UInt jc = 0; jc < nc; jc++ )
                {
                    assembleMatrix ( *jacobian,
                                     *this->M_elmatK,
                                     this->M_FESpace->fe(),
                                     this->M_FESpace->dof(),
                                     ic, jc,
                                     this->M_offset +  ic * totalDof, this->M_offset +  jc * totalDof );
                }
            }
        }
    }
}