ldl.hh

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// SPDX-FileCopyrightText: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
#ifndef DUNE_ISTL_LDL_HH
#define DUNE_ISTL_LDL_HH
 
#if HAVE_SUITESPARSE_LDL || defined DOXYGEN
 
#include <memory>
#include <type_traits>
 
#ifdef __cplusplus
extern "C"
{
#include <ldl.h>
#include <amd.h>
}
#endif
 
#include <dune/common/exceptions.hh>
 
#include <dune/istl/bccsmatrixinitializer.hh>
#include <dune/istl/defaultmatrixvectortraits.hh>
#include <dune/istl/foreach.hh>
#include <dune/istl/solvers.hh>
#include <dune/istl/solvertype.hh>
#include <dune/istl/solverregistry.hh>
 
namespace Dune {
  // forward declarations
  template<class M, class T, class TM, class TD, class TA>
  class SeqOverlappingSchwarz;
 
  template<class T, bool tag>
  struct SeqOverlappingSchwarzAssemblerHelper;
 
  template<typename M>
  class LDL : public InverseOperator<
    typename DefaultMatrixVectorTraits<M>::domain_type,
    typename DefaultMatrixVectorTraits<M>::range_type>
  {
    public:
    typedef M Matrix;
    typedef M matrix_type;
    typedef typename FieldTraits<M>::field_type field_type;
 
    typedef Dune::ISTL::Impl::BCCSMatrix<field_type,int> LDLMatrix;
    typedef ISTL::Impl::BCCSMatrixInitializer<M, int> MatrixInitializer;
    typedef typename DefaultMatrixVectorTraits<M>::domain_type domain_type;
    typedef typename DefaultMatrixVectorTraits<M>::range_type range_type;
 
    SolverCategory::Category category() const override
    {
      return SolverCategory::Category::sequential;
    }
 
    LDL(const Matrix& matrix, int verbose=0) : matrixIsLoaded_(false), verbose_(verbose)
    {
      //check whether T is a supported type
      static_assert(std::is_same<field_type,double>::value,"Unsupported Type in LDL (only double supported)");
      setMatrix(matrix);
    }
 
    LDL(const Matrix& matrix, int verbose, bool) : matrixIsLoaded_(false), verbose_(verbose)
    {
      //check whether T is a supported type
      static_assert(std::is_same<field_type,double>::value,"Unsupported Type in LDL (only double supported)");
      setMatrix(matrix);
    }
 
    LDL(const Matrix& matrix, const ParameterTree& config)
      : LDL(matrix, config.get<int>("verbose", 0))
    {}
 
    LDL() : matrixIsLoaded_(false), verbose_(0)
    {}
 
    virtual ~LDL()
    {
      if ((ldlMatrix_.N() + ldlMatrix_.M() > 0) || matrixIsLoaded_)
        free();
    }
 
  public:
    void apply(domain_type& x, range_type& b, InverseOperatorResult& res) override
    {
      BlockVector<field_type> B(ldlMatrix_.N()), X(ldlMatrix_.M());
      Impl::flatVectorForEachMasked(b, maskVector_, [&](auto const& b_i, std::size_t i) { B[i] = b_i; });
      apply(X.data(), B.data());
      Impl::flatVectorForEachMasked(x, maskVector_, [&](auto& x_i, std::size_t i) { x_i = X[i]; });
 
      // this is a direct solver
      res.iterations = 1;
      res.converged = true;
    }
 
    void apply(domain_type& x, range_type& b, [[maybe_unused]] double reduction, InverseOperatorResult& res) override
    {
      apply(x,b,res);
    }
 
    void apply(field_type* x, field_type* b)
    {
      const int dimMat(ldlMatrix_.N());
      ldl_perm(dimMat, Y_, b, P_);
      ldl_lsolve(dimMat, Y_, Lp_, Li_, Lx_);
      ldl_dsolve(dimMat, Y_, D_);
      ldl_ltsolve(dimMat, Y_, Lp_, Li_, Lx_);
      ldl_permt(dimMat, x, Y_, P_);
    }
 
    void setOption([[maybe_unused]] unsigned int option, [[maybe_unused]] double value)
    {}
 
    void setMatrix(const Matrix& matrix)
    {
      if ((ldlMatrix_.N() + ldlMatrix_.M() > 0) || matrixIsLoaded_)
        free();
 
      if (ldlMatrix_.N() + ldlMatrix_.M() + ldlMatrix_.nonzeroes() != 0)
        ldlMatrix_.free();
      ldlMatrix_.setSize(MatrixDimension<Matrix>::rowdim(matrix),
                         MatrixDimension<Matrix>::coldim(matrix));
      MatrixInitializer initializer(ldlMatrix_);
 
      copyToBCCSMatrix(initializer, matrix);
 
      maskVector_.clear();
      maskVector_.resize(matrix.N(), true);
 
      decompose();
    }
 
    template<class S>
    void setSubMatrix(const Matrix& matrix, const S& rowIndexSet)
    {
      if ((ldlMatrix_.N() + ldlMatrix_.M() > 0) || matrixIsLoaded_)
        free();
 
      if (ldlMatrix_.N() + ldlMatrix_.M() + ldlMatrix_.nonzeroes() != 0)
        ldlMatrix_.free();
 
      ldlMatrix_.setSize(rowIndexSet.size()*MatrixDimension<Matrix>::rowdim(matrix) / matrix.N(),
                         rowIndexSet.size()*MatrixDimension<Matrix>::coldim(matrix) / matrix.M());
      MatrixInitializer initializer(ldlMatrix_);
 
      copyToBCCSMatrix(initializer, ISTL::Impl::MatrixRowSubset<Matrix,std::set<std::size_t> >(matrix,rowIndexSet));
 
      maskVector_.clear();
      maskVector_.resize(matrix.N(), false);
      for (auto i : rowIndexSet)
        maskVector_[i] = true;
 
      decompose();
    }
 
    inline void setVerbosity(int v)
    {
      verbose_=v;
    }
 
    inline LDLMatrix& getInternalMatrix()
    {
      return ldlMatrix_;
    }
 
    void free()
    {
      delete [] D_;
      delete [] Y_;
      delete [] Lp_;
      delete [] Lx_;
      delete [] Li_;
      delete [] P_;
      delete [] Pinv_;
      ldlMatrix_.free();
      matrixIsLoaded_ = false;
    }
 
    inline const char* name()
    {
      return "LDL";
    }
 
    inline double* getD()
    {
      return D_;
    }
 
    inline int* getLp()
    {
      return Lp_;
    }
 
    inline int* getLi()
    {
      return Li_;
    }
 
    inline double* getLx()
    {
      return Lx_;
    }
 
    private:
    template<class,class,class,class,class>
    friend class SeqOverlappingSchwarz;
 
    friend struct SeqOverlappingSchwarzAssemblerHelper<LDL<Matrix>,true>;
 
    void decompose()
    {
      // allocate vectors
      const int dimMat(ldlMatrix_.N());
      D_ = new double [dimMat];
      Y_ = new double [dimMat];
      Lp_ = new int [dimMat + 1];
      Parent_ = new int [dimMat];
      Lnz_ = new int [dimMat];
      Flag_ = new int [dimMat];
      Pattern_ = new int [dimMat];
      P_ = new int [dimMat];
      Pinv_ = new int [dimMat];
 
      double Info [AMD_INFO];
      if(amd_order (dimMat, ldlMatrix_.getColStart(), ldlMatrix_.getRowIndex(), P_, (double *) NULL, Info) < AMD_OK)
        DUNE_THROW(InvalidStateException,"Error: AMD failed!");
      if(verbose_ > 0)
        amd_info (Info);
      // compute the symbolic factorisation
      ldl_symbolic(dimMat, ldlMatrix_.getColStart(), ldlMatrix_.getRowIndex(), Lp_, Parent_, Lnz_, Flag_, P_, Pinv_);
      // initialise those entries of additionalVectors_ whose dimension is known only now
      Lx_ = new double [Lp_[dimMat]];
      Li_ = new int [Lp_[dimMat]];
      // compute the numeric factorisation
      const int rank(ldl_numeric(dimMat, ldlMatrix_.getColStart(), ldlMatrix_.getRowIndex(), ldlMatrix_.getValues(),
                                 Lp_, Parent_, Lnz_, Li_, Lx_, D_, Y_, Pattern_, Flag_, P_, Pinv_));
      // free temporary vectors
      delete [] Flag_;
      delete [] Pattern_;
      delete [] Parent_;
      delete [] Lnz_;
 
      if(rank!=dimMat)
        DUNE_THROW(InvalidStateException,"Error: LDL factorisation failed!");
    }
 
    LDLMatrix ldlMatrix_;
    bool matrixIsLoaded_;
    int verbose_;
    int* Lp_;
    int* Parent_;
    int* Lnz_;
    int* Flag_;
    int* Pattern_;
    int* P_;
    int* Pinv_;
    double* D_;
    double* Y_;
    double* Lx_;
    int* Li_;
 
    std::vector<bool> maskVector_;
  };
 
  template<typename M>
  struct IsDirectSolver<LDL<M> >
  {
    enum {value = true};
  };
 
  template<typename T, typename A>
  struct StoresColumnCompressed<LDL<BCRSMatrix<T,A> > >
  {
    enum {value = true};
  };
 
  DUNE_REGISTER_SOLVER("ldl",
                       [](auto opTraits, const auto& op, const Dune::ParameterTree& config)
                       -> std::shared_ptr<typename decltype(opTraits)::solver_type>
                       {
                         using OpTraits = decltype(opTraits);
                         using M = typename OpTraits::matrix_type;
                         // works only for sequential operators
                         if constexpr (OpTraits::isParallel){
                           if(opTraits.getCommOrThrow(op).communicator().size() > 1)
                             DUNE_THROW(Dune::InvalidStateException, "LDL works only for sequential operators.");
                         }
                         // check if LDL<M>* is convertible to
                         // InverseOperator*. This allows only the explicit
                         // specialized variants of LDL
                         if constexpr (std::is_convertible_v<LDL<M>*,
                                       Dune::InverseOperator<typename OpTraits::domain_type,
                                       typename OpTraits::range_type>*> &&
                                       std::is_same_v<typename FieldTraits<M>::field_type, double>
                                       ){
                           const auto& A = opTraits.getAssembledOpOrThrow(op);
                           const M& mat = A->getmat();
                           int verbose = config.get("verbose", 0);
                           return std::make_shared<LDL<M>>(mat,verbose);
                         }
                         DUNE_THROW(UnsupportedType,
                                    "Unsupported Type in LDL (only FieldMatrix<double,...> supported)");
                       });
 
} // end namespace Dune
 
 
#endif //HAVE_SUITESPARSE_LDL
#endif //DUNE_ISTL_LDL_HH