Masse_DG_base.h

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#ifndef Masse_DG_base_included
#define Masse_DG_base_included
 
#include <Solveur_Masse_base.h>
#include <TRUST_Ref.h>
 
class Domaine_Cl_DG;
class Domaine_DG;
 
/**
 * @brief Abstract base class for the DG mass matrix operator.
 *
 * This class assembles and applies the element-wise L2 mass matrix arising in the
 * DG time discretization. The mass term appears in the implicit time scheme as:
 *   (M/dt) * u^{n+1} = (M/dt) * u^n + RHS
 *
 * Two assembly strategies are supported depending on whether the basis is
 * orthonormalized via Gram-Schmidt (gram_schmidt flag on Domaine_DG):
 *
 *  - **Orthonormal basis** (gram_schmidt == true): The mass matrix is diagonal,
 *    with entries equal to the element volume (since the basis is L2-normalized
 *    by volume). The sparsity pattern is therefore purely diagonal (nb_bfunc
 *    entries per element per spatial dimension).
 *
 *  - **Non-orthonormal basis** (gram_schmidt == false): The mass matrix is a dense
 *    nb_bfunc x nb_bfunc block per element, assembled by numerical quadrature as
 *    M_ij = integral of phi_i * phi_j. The sparsity pattern is a full local block.
 *
 * An optional temporal coefficient (e.g., density or porosity) can be applied
 * element-wise via appliquer_coef(), which multiplies the mass entries by a field
 * retrieved by name from the equation (name_of_coefficient_temporel_).
 *
 * Derived classes must implement appliquer_impl(), which applies M^{-1} to a
 * right-hand side vector (used for explicit time stepping or lumped-mass inversion).
 *
 * @sa Masse_DG_Elem, Solveur_Masse_base
 */
class Masse_DG_base : public Solveur_Masse_base
{
  Declare_base(Masse_DG_base);
public:
 
  void associer_domaine_dis_base(const Domaine_dis_base& ) override;
  void associer_domaine_cl_dis_base(const Domaine_Cl_dis_base& ) override;
  void appliquer_coef(DoubleVect& coef) const;
 
  inline int has_interface_blocs() const override { return 1; }
  void dimensionner_blocs(matrices_t matrices, const tabs_t& semi_impl) const override;
  void ajouter_blocs(matrices_t matrices, DoubleTab& secmem, double dt, const tabs_t& semi_impl, int resoudre_en_increments) const override;
 
protected:
  OBS_PTR(Domaine_DG) le_dom_dg_;
  OBS_PTR(Domaine_Cl_DG) le_dom_Cl_dg_;
};
 
#endif /* Masse_DG_base_included */