// ============================================================================
// ==                                                                        ==
// == AMDiS - Adaptive multidimensional simulations                          ==
// ==                                                                        ==
// ==  http://www.amdis-fem.org                                              ==
// ==                                                                        ==
// ============================================================================
//
// Software License for AMDiS
//
// Copyright (c) 2010 Dresden University of Technology 
// All rights reserved.
// Authors: Simon Vey, Thomas Witkowski et al.
//
// This file is part of AMDiS
//
// See also license.opensource.txt in the distribution.



/** \file PetscHelper.h */

#ifndef AMDIS_PETSCHELPER_H
#define AMDIS_PETSCHELPER_H

#include <mpi.h>
#include <map>
#include <vector>
#include <petsc.h>

namespace AMDiS {

  using namespace std;

  /** \brief
   * In this namespace, we collect several auxiliary functions for using
   * PETSc in AMDiS. Many of these function may be replaced by new PETSc 
   * function in upcoming versions.
   */
  namespace petsc_helper {

    /// Defines a PETSc matrix column wise
    typedef pair<vector<int>, vector<double> > SparseCol;
    typedef map<int, SparseCol> PetscMatCol;

    /** \brief
     * Returns for a distributed matrix on each rank the local matrix in a
     * sparce column format.
     *
     * \param[in]   mat     PETSc distributerd matrix.
     * \param[out]  matCol  The sparse column represenation of the local matrix.
     */
    void getMatLocalColumn(Mat mat, PetscMatCol &matCol);

    /** \brief
     * Set a local column vector in a distributed matrix.
     *
     * \param[out]  mat     Distributed matrix.
     * \param[in]   column  Column index.
     * \param[in]   vec     Column vector.
     */
    void setMatLocalColumn(Mat mat, int column, Vec vec);

    /** \brief
     * Create a local PETSc vector representing the column of a matrix
     * stored in \ref PetscMatCol type format.
     *
     * \param[in]   column   Sparse column representation.
     * \param[out]  vec      Vector representing one column of the matrix.
     */
    void getColumnVec(const SparseCol &matCol, Vec vec);

    /** \brief
     * Computes the matrix matrix product inv(A) B = C. Matrices B and C
     * are distributed matrices. Matrix A is a local matrix on each MPI
     * task. The overall number of rows of local matrices A must be the
     * number of distriubted rows in B.
     *
     * \param[in]   ksp   inv(A) matrix given by a PETSc solver object.
     * \param[in]   mat0  matrix B
     * \param[out]  mat1  resulting matrix C, is created inside the function
     */
    void blockMatMatSolve(KSP ksp, Mat mat0, Mat &mat1);

    /** \brief
     * Converts a 2x2 nested matrix to a MATAIJ matrix (thus not nested).
     *
     * \param[in]  matNest  nested input matrix
     * \param[out] mat      matrix of type MATAIJ, created inside this function.
     */
    void matNestConvert(Mat matNest, Mat &mat);
  }

}

#endif