text: /* ************************************************************************
   * Copyright (c) 2018-2020 Advanced Micro Devices, Inc.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
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   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
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   * ************************************************************************ */
  
  #ifndef ROCALUTION_PRECONDITIONER_SADDLEPOINT_HPP_
  #define ROCALUTION_PRECONDITIONER_SADDLEPOINT_HPP_
  
  #include "../../base/local_vector.hpp"
  #include "../solver.hpp"
  #include "preconditioner.hpp"
  
  #include <vector>
  
  namespace rocalution
  {
  
      /** \ingroup precond_module
    * \class DiagJacobiSaddlePointPrecond
    * \brief Diagonal Preconditioner for Saddle-Point Problems
    * \details
    * Consider the following saddle-point problem
    * \f[
    *   A = \begin{pmatrix} K & F \\ E & 0 \end{pmatrix}.
    * \f]
    * For such problems we can construct a diagonal Jacobi-type preconditioner of type
    * \f[
    *   P = \begin{pmatrix} K & 0 \\ 0 & S \end{pmatrix},
    * \f]
    * with \f$S=ED^{-1}F\f$, where \f$D\f$ are the diagonal elements of \f$K\f$. The matrix
    * \f$S\f$ is fully constructed (via sparse matrix-matrix multiplication). The
    * preconditioner needs to be initialized with two external solvers/preconditioners -
    * one for the matrix \f$K\f$ and one for the matrix \f$S\f$.
    *
    * \tparam OperatorType - can be LocalMatrix
    * \tparam VectorType - can be LocalVector
    * \tparam ValueType - can be float, double, std::complex<float> or std::complex<double>
    */
      template <class OperatorType, class VectorType, typename ValueType>
      class DiagJacobiSaddlePointPrecond : public Preconditioner<OperatorType, VectorType, ValueType>
      {
      public:
          DiagJacobiSaddlePointPrecond();
          virtual ~DiagJacobiSaddlePointPrecond();
  
          virtual void Print(void) const;
          virtual void Clear(void);
  
          /** \brief Initialize solver for \f$K\f$ and \f$S\f$ */
          void Set(Solver<OperatorType, VectorType, ValueType>& K_Solver,
                   Solver<OperatorType, VectorType, ValueType>& S_Solver);
  
          virtual void Build(void);
  
          virtual void Solve(const VectorType& rhs, VectorType* x);
  
      protected:
          /** \brief A_ is decomposed into \f$[K,F;E,0]\f$ */
          OperatorType A_;
          /** \brief Operator \f$K\f$ */
          OperatorType K_;
          /** \brief Operator \f$S\f$ */
          OperatorType S_;
  
          /** \brief The sizes of the \f$K\f$ matrix */
          int K_nrow_;
          /** \brief The sizes of the \f$K\f$ matrix */
          int K_nnz_;
  
          /** \brief Keep the precond matrix in CSR or not */
          bool op_mat_format_;
          /** \brief Precond matrix format */
          unsigned int precond_mat_format_;
  
          /** \brief Vector x_ */
          VectorType x_;
          /** \brief Vector x_1_ */
          VectorType x_1_;
          /** \brief Vector x_2_ */
          VectorType x_2_;
          /** \brief Vector x_1tmp_ */
          VectorType x_1tmp_;
  
          /** \brief Vector rhs_ */
          VectorType rhs_;
          /** \brief Vector rhs_1_ */
          VectorType rhs_1_;
          /** \brief Vector rhs_2_ */
          VectorType rhs_2_;
  
          /** \brief Solver for \f$K\f$ */
          Solver<OperatorType, VectorType, ValueType>* K_solver_;
          /** \brief Solver for \f$S\f$ */
          Solver<OperatorType, VectorType, ValueType>* S_solver_;
  
          /** \brief Permutation vector */
          LocalVector<int> permutation_;
          /** \brief Size */
          int size_;
  
          virtual void MoveToHostLocalData_(void);
          virtual void MoveToAcceleratorLocalData_(void);
      };
  
  } // namespace rocalution
  
  #endif // ROCALUTION_PRECONDITIONER_SADDLEPOINT_HPP_
  