default_linear_solver.hh

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#pragma once
 
// DiFfRG
#include <DiFfRG/common/linear_algebra.hh>
#include <DiFfRG/timestepping/linear_solver/PETScDirect.hh>
#include <DiFfRG/timestepping/linear_solver/PETScKrylov.hh>
#include <DiFfRG/timestepping/linear_solver/UMFPack.hh>
 
namespace DiFfRG
{
  namespace internal
  {
    template <typename SparseMatrixType, typename VectorType> struct _default_solver {
      using type = UMFPack<SparseMatrixType, VectorType>;
    };
 
#ifdef DEAL_II_WITH_PETSC
    // PETScDirect is declared only when deal.II reports PETSc was built with MUMPS -- the whole
    // class sits inside that guard -- so the choice has to be made by the preprocessor here. An
    // `if constexpr` would not help: the name must be visible for this to parse at all.
    template <> struct _default_solver<dealii::PETScWrappers::MPI::SparseMatrix, dealii::PETScWrappers::MPI::Vector> {
#ifdef DEAL_II_PETSC_WITH_MUMPS
      using type = PETScDirect<dealii::PETScWrappers::MPI::SparseMatrix, dealii::PETScWrappers::MPI::Vector>;
#else
      using type = PETScKrylov<dealii::PETScWrappers::MPI::SparseMatrix, dealii::PETScWrappers::MPI::Vector>;
#endif
    };
#endif
  } // namespace internal
 
  template <typename SparseMatrixType, typename VectorType>
  using DefaultLinearSolver = typename internal::_default_solver<SparseMatrixType, VectorType>::type;
} // namespace DiFfRG