spqr.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_SPQR_HH
#define DUNE_ISTL_SPQR_HH
 
#if HAVE_SUITESPARSE_SPQR || defined DOXYGEN
 
#include <complex>
#include <type_traits>
 
#include <SuiteSparseQR.hpp>
 
#include <dune/common/exceptions.hh>
 
#include <dune/istl/bccsmatrixinitializer.hh>
#include <dune/istl/solvers.hh>
#include <dune/istl/solvertype.hh>
#include <dune/istl/solverfactory.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<class Matrix>
  class SPQR
  {};
 
  template<typename T, typename A, int n, int m>
  class SPQR<BCRSMatrix<FieldMatrix<T,n,m>,A > >
    : public InverseOperator<BlockVector<FieldVector<T,m>, typename std::allocator_traits<A>::template rebind_alloc<FieldVector<T,m> > >,
                             BlockVector<FieldVector<T,n>, typename std::allocator_traits<A>::template rebind_alloc<FieldVector<T,n> > > >
  {
    public:
    typedef Dune::BCRSMatrix<FieldMatrix<T,n,m>,A> Matrix;
    typedef Dune::BCRSMatrix<FieldMatrix<T,n,m>,A> matrix_type;
    typedef ISTL::Impl::BCCSMatrix<T,int> SPQRMatrix;
    typedef ISTL::Impl::BCCSMatrixInitializer<BCRSMatrix<FieldMatrix<T,n,m>,A>, int> MatrixInitializer;
    typedef Dune::BlockVector<FieldVector<T,m>, typename std::allocator_traits<A>::template rebind_alloc<FieldVector<T,m> > > domain_type;
    typedef Dune::BlockVector<FieldVector<T,n>, typename std::allocator_traits<A>::template rebind_alloc<FieldVector<T,n> > > range_type;
 
    SolverCategory::Category category() const override
    {
      return SolverCategory::Category::sequential;
    }
 
    SPQR(const Matrix& matrix, int verbose=0) : matrixIsLoaded_(false), verbose_(verbose)
    {
      //check whether T is a supported type
      static_assert((std::is_same<T,double>::value) || (std::is_same<T,std::complex<double> >::value),
                    "Unsupported Type in SPQR (only double and std::complex<double> supported)");
      cc_ = new cholmod_common();
      cholmod_l_start(cc_);
      setMatrix(matrix);
    }
 
    SPQR(const Matrix& matrix, int verbose, bool) : matrixIsLoaded_(false), verbose_(verbose)
    {
      //check whether T is a supported type
      static_assert((std::is_same<T,double>::value) || (std::is_same<T,std::complex<double> >::value),
                    "Unsupported Type in SPQR (only double and std::complex<double> supported)");
      cc_ = new cholmod_common();
      cholmod_l_start(cc_);
      setMatrix(matrix);
    }
 
    SPQR(const Matrix& matrix, const ParameterTree& config)
      : SPQR(matrix, config.get<int>("verbose", 0))
    {}
 
    SPQR() : matrixIsLoaded_(false), verbose_(0)
    {
      //check whether T is a supported type
      static_assert((std::is_same<T,double>::value) || (std::is_same<T,std::complex<double> >::value),
                    "Unsupported Type in SPQR (only double and std::complex<double> supported)");
      cc_ = new cholmod_common();
      cholmod_l_start(cc_);
    }
 
    virtual ~SPQR()
    {
      if ((spqrMatrix_.N() + spqrMatrix_.M() > 0) || matrixIsLoaded_)
        free();
      cholmod_l_finish(cc_);
    }
 
    void apply(domain_type& x, range_type& b, InverseOperatorResult& res) override
    {
      const std::size_t numRows(spqrMatrix_.N());
      // fill B
      for(std::size_t k = 0; k != numRows/n; ++k)
        for (int l = 0; l < n; ++l)
          (static_cast<T*>(B_->x))[n*k+l] = b[k][l];
 
      cholmod_dense* BTemp = B_;
      B_ = SuiteSparseQR_qmult<T>(0, spqrfactorization_, B_, cc_);
      cholmod_dense* X = SuiteSparseQR_solve<T>(1, spqrfactorization_, B_, cc_);
      cholmod_l_free_dense(&BTemp, cc_);
 
      const std::size_t numCols(spqrMatrix_.M());
      // fill x
      for(std::size_t k = 0; k != numCols/m; ++k)
        for (int l = 0; l < m; ++l)
          x[k][l] = (static_cast<T*>(X->x))[m*k+l];
 
      cholmod_l_free_dense(&X, cc_);
      // this is a direct solver
      res.iterations = 1;
      res.converged = true;
      if(verbose_ > 0)
      {
        std::cout<<std::endl<<"Solving with SuiteSparseQR"<<std::endl;
        std::cout<<"Flops Taken: "<<cc_->SPQR_flopcount<<std::endl;
        std::cout<<"Analysis Time: "<<cc_->SPQR_analyze_time<<" s"<<std::endl;
        std::cout<<"Factorize Time: "<<cc_->SPQR_factorize_time<<" s"<<std::endl;
        std::cout<<"Backsolve Time: "<<cc_->SPQR_solve_time<<" s"<<std::endl;
        std::cout<<"Peak Memory Usage: "<<cc_->memory_usage<<" bytes"<<std::endl;
        std::cout<<"Rank Estimate: "<<cc_->SPQR_istat[4]<<std::endl<<std::endl;
      }
    }
 
    void apply (domain_type& x, range_type& b, [[maybe_unused]] double reduction, InverseOperatorResult& res) override
    {
      apply(x, b, res);
    }
 
    void setOption([[maybe_unused]] unsigned int option, [[maybe_unused]] double value)
    {}
 
    void setMatrix(const Matrix& matrix)
    {
      if ((spqrMatrix_.N() + spqrMatrix_.M() > 0) || matrixIsLoaded_)
        free();
 
      if (spqrMatrix_.N() + spqrMatrix_.M() + spqrMatrix_.nonzeroes() != 0)
        spqrMatrix_.free();
      spqrMatrix_.setSize(MatrixDimension<Matrix>::rowdim(matrix),
                          MatrixDimension<Matrix>::coldim(matrix));
      ISTL::Impl::BCCSMatrixInitializer<Matrix, int> initializer(spqrMatrix_);
 
      copyToBCCSMatrix(initializer, matrix);
 
      decompose();
    }
 
    template<class S>
    void setSubMatrix(const Matrix& matrix, const S& rowIndexSet)
    {
      if ((spqrMatrix_.N() + spqrMatrix_.M() > 0) || matrixIsLoaded_)
        free();
 
      if (spqrMatrix_.N() + spqrMatrix_.M() + spqrMatrix_.nonzeroes() != 0)
        spqrMatrix_.free();
 
      spqrMatrix_.setSize(rowIndexSet.size()*MatrixDimension<Matrix>::rowdim(matrix) / matrix.N(),
                          rowIndexSet.size()*MatrixDimension<Matrix>::coldim(matrix) / matrix.M());
      ISTL::Impl::BCCSMatrixInitializer<Matrix, int> initializer(spqrMatrix_);
 
      copyToBCCSMatrix(initializer, ISTL::Impl::MatrixRowSubset<Matrix,std::set<std::size_t> >(matrix,rowIndexSet));
 
      decompose();
    }
 
    inline void setVerbosity(int v)
    {
      verbose_=v;
    }
 
    inline SuiteSparseQR_factorization<T>* getFactorization()
    {
      return spqrfactorization_;
    }
 
    inline SPQRMatrix& getInternalMatrix()
    {
      return spqrMatrix_;
    }
 
    void free()
    {
      cholmod_l_free_sparse(&A_, cc_);
      cholmod_l_free_dense(&B_, cc_);
      SuiteSparseQR_free<T>(&spqrfactorization_, cc_);
      spqrMatrix_.free();
      matrixIsLoaded_ = false;
    }
 
    inline const char* name()
    {
      return "SPQR";
    }
 
    private:
    template<class M,class X, class TM, class TD, class T1>
    friend class SeqOverlappingSchwarz;
 
    friend struct SeqOverlappingSchwarzAssemblerHelper<SPQR<Matrix>,true>;
 
    void decompose()
    {
      const std::size_t nrows(spqrMatrix_.N());
      const std::size_t ncols(spqrMatrix_.M());
      const std::size_t nnz(spqrMatrix_.getColStart()[ncols]);
 
      // initialise the matrix A (sorted, packed, unsymmetric, real entries)
      A_ = cholmod_l_allocate_sparse(nrows, ncols, nnz, 1, 1, 0, 1, cc_);
 
      // copy all the entries of Ap, Ai, Ax
      for(std::size_t k = 0; k != (ncols+1); ++k)
        (static_cast<long int *>(A_->p))[k] = spqrMatrix_.getColStart()[k];
 
      for(std::size_t k = 0; k != nnz; ++k)
      {
        (static_cast<long int*>(A_->i))[k] = spqrMatrix_.getRowIndex()[k];
        (static_cast<T*>(A_->x))[k] = spqrMatrix_.getValues()[k];
      }
 
      // initialise the vector B
      B_ = cholmod_l_allocate_dense(nrows, 1, nrows, A_->xtype, cc_);
      // compute factorization of A
      spqrfactorization_=SuiteSparseQR_factorize<T>(SPQR_ORDERING_DEFAULT,SPQR_DEFAULT_TOL,A_,cc_);
    }
 
    SPQRMatrix spqrMatrix_;
    bool matrixIsLoaded_;
    int verbose_;
    cholmod_common* cc_;
    cholmod_sparse* A_;
    cholmod_dense* B_;
    SuiteSparseQR_factorization<T>* spqrfactorization_;
  };
 
  template<typename T, typename A>
  struct IsDirectSolver<SPQR<BCRSMatrix<T,A> > >
  {
    enum {value = true};
  };
 
  template<typename T, typename A>
  struct StoresColumnCompressed<SPQR<BCRSMatrix<T,A> > >
  {
    enum {value = true};
  };
 
  DUNE_REGISTER_SOLVER("spqr",
                       [](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, "SPQR works only for sequential operators.");
                         }
                         // check if SPQR<M>* is convertible to
                         // InverseOperator*. This allows only the explicit
                         // specialized variants of SPQR
                         // std::complex is temporary disabled, because it fails if libc++ is used
                         if constexpr (std::is_convertible_v<SPQR<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<Dune::SPQR<M>>(mat,verbose);
                         }
                         DUNE_THROW(UnsupportedType,
                                    "Unsupported Type in SPQR (only FieldMatrix<double,...> supported)");
                       });
 
} // end namespace Dune
 
 
#endif //HAVE_SUITESPARSE_SPQR
#endif //DUNE_ISTL_SPQR_HH