Method getMassMatrix

tools/Assembler/ref/Assembler2D.cpp:69–114

}

ZSparseMatrix Assembler2D::getMassMatrix(bool lumped, int repeats) {
    double p = m_density;

    typedef Eigen::Triplet<double> T;
    std::vector<T> triplets;

    if (lumped) {
        for (size_t i=0; i<m_mesh->getNbrElements(); i++) {
            VectorI idx = m_mesh->getElement(i);
            assert(idx.size() == 3);
            double V = m_mesh->getElementVolume(i);

            for (size_t j=0; j<idx.size(); j++)
                for (size_t l=0; l<repeats; l++)
                    triplets.push_back(T(repeats*idx[j]+l,
                                repeats*idx[j]+l, p*V/3.0));
        }
    } else {
        double coeff_jj = 1.0 / 6.0,
               coeff_jk = 1.0 / 12.0;
        for (size_t i=0; i<m_mesh->getNbrElements(); ++i) {
            VectorI idx = m_mesh->getElement(i);
            assert(idx.size() == 3);
            double V = m_mesh->getElementVolume(i);

            for (size_t j=0; j<3; ++j) {
                for (size_t k=0; k<3; ++k) {
                    if (idx[j] == idx[k]) {
                        for (size_t l=0; l<repeats; ++l)
                            triplets.push_back(
                                    T(repeats*idx[j]+l, repeats*idx[k]+l, p*V*coeff_jj));
                    } else {
                        for (size_t l=0; l<repeats; ++l)
                            triplets.push_back(
                                    T(repeats*idx[j]+l, repeats*idx[k]+l, p*V*coeff_jk));
                    }
                }
            }
        }
    }

    Eigen::SparseMatrix<double> M = Eigen::SparseMatrix<double>(
            repeats*m_mesh->getNbrNodes(), repeats*m_mesh->getNbrNodes());
    M.setFromTriplets(triplets.begin(), triplets.end());
    return ZSparseMatrix(M);
}

ZSparseMatrix Assembler2D::getStiffnessMatrix() {
    // Elastic modulii