MonodomainPurkinjeCableMassMatrixAssembler.hpp

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*/

#ifndef MONODOMAINPURKINJECABLEMASSMATRIXASSEMBLER_HPP_
#define MONODOMAINPURKINJECABLEMASSMATRIXASSEMBLER_HPP_

#include "AbstractFeCableIntegralAssembler.hpp"
#include "HeartConfig.hpp"

template<unsigned ELEMENT_DIM, unsigned SPACE_DIM>
class MonodomainPurkinjeCableMassMatrixAssembler : public AbstractFeCableIntegralAssembler<ELEMENT_DIM,SPACE_DIM,2,false,true,NORMAL>
{
private:
    static const unsigned CABLE_ELEMENT_DIM = 1;

    static const unsigned NUM_CABLE_ELEMENT_NODES = 2;

    bool mUseMassLumping;

public:
    c_matrix<double,2*NUM_CABLE_ELEMENT_NODES,2*NUM_CABLE_ELEMENT_NODES/*2=PROBLEM_DIM here*/>
        ComputeCableMatrixTerm(
            c_vector<double, NUM_CABLE_ELEMENT_NODES>& rPhi,
            c_matrix<double, SPACE_DIM, NUM_CABLE_ELEMENT_NODES>& rGradPhi,
            ChastePoint<SPACE_DIM>& rX,
            c_vector<double,2>& rU,
            c_matrix<double,2, SPACE_DIM>& rGradU,
            Element<CABLE_ELEMENT_DIM,SPACE_DIM>* pElement)
    {
        c_matrix<double,4, 4> ret = zero_matrix<double>(4, 4);

        //We have to scale the assembled matrix by the cross sectional area of the Purkinje
        //fibre to ensure conservation of current at branch points. See #1899.
        const double fibre_cross_section_area = M_PI*pElement->GetAttribute()*pElement->GetAttribute();

        for(unsigned i=0; i<2; i++) // 2 = number of basis functions per cable element
        {
            for(unsigned j=0; j<2; j++)  // 2 = number of basis functions per cable element
            {
                ret(2*i,  2*j)   = 0;  // [V,V] block
                ret(2*i+1,2*j)   = 0;  // [Vpurkinje,V] block
                ret(2*i,  2*j+1) = 0;  // [V,Vpurkinje] block
                ret(2*i+1,2*j+1) = rPhi(i)*rPhi(j);

                ret(2*i+1,2*j+1) *= fibre_cross_section_area;
            }
        }

        if (mUseMassLumping)
        {
            // not implemented yet (and also not implemented yet in MonodomainPurkinjeVolumeMassMatrixAssembler)
            NEVER_REACHED;
        }

        return ret;
    }

    MonodomainPurkinjeCableMassMatrixAssembler(MixedDimensionMesh<ELEMENT_DIM,SPACE_DIM>* pMesh, bool useMassLumping=false)
       : AbstractFeCableIntegralAssembler<ELEMENT_DIM,SPACE_DIM,2,false,true,NORMAL>(pMesh),
         mUseMassLumping(useMassLumping)
    {
    }
};

#endif /*MONODOMAINPURKINJECABLEMASSMATRIXASSEMBLER_HPP_*/