Masse_DG_Elem.h

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#ifndef Masse_DG_Elem_included
#define Masse_DG_Elem_included
 
#include <Masse_DG_base.h>
 
/**
 * @brief Concrete DG mass operator for element-based unknowns.
 *
 * This class provides the implementation of appliquer_impl(), which applies the
 * inverse mass matrix M^{-1} to a right-hand side vector. It is used for explicit
 * time stepping or for any operation requiring M^{-1} * v element-by-element.
 *
 * Two strategies are used depending on the basis orthonormalization flag:
 *  - **Orthonormal basis**: M is diagonal with entries equal to element volumes,
 *    so M^{-1} * v reduces to a simple element-wise division by volume via
 *    tab_divide_any_shape().
 *  - **Non-orthonormal basis**: M^{-1} is computed locally per element via
 *    BasisFunction::eval_invMassMatrix() and applied by a dense matrix-vector
 *    product for each spatial component independently.
 *
 * @sa Masse_DG_base, BasisFunction::eval_invMassMatrix
 */
class Masse_DG_Elem: public Masse_DG_base
{
  Declare_instanciable(Masse_DG_Elem);
public:
  DoubleTab& appliquer_impl(DoubleTab&) const override;
};
 
#endif /* Masse_DG_Elem_included */