// -*- c++ -*- (enables emacs c++ mode)
//===========================================================================
//
// Copyright (C) 2002-2008 Yves Renard
//
// This file is a part of GETFEM++
//
// Getfem++  is  free software;  you  can  redistribute  it  and/or modify it
// under  the  terms  of the  GNU  Lesser General Public License as published
// by  the  Free Software Foundation;  either version 2.1 of the License,  or
// (at your option) any later version.
// This program  is  distributed  in  the  hope  that it will be useful,  but
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or  FITNESS  FOR  A PARTICULAR PURPOSE.  See the GNU Lesser General Public
// License for more details.
// You  should  have received a copy of the GNU Lesser General Public License
// along  with  this program;  if not, write to the Free Software Foundation,
// Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
//
// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
//
//===========================================================================

/** @file gmm_matrix.h
   @author  Yves Renard <Yves.Renard@insa-lyon.fr>
   @date October 13, 2002.
    @brief Declaration of some matrix types (gmm::dense_matrix,
    gmm::row_matrix, gmm::col_matrix, gmm::csc_matrix, etc.)
*/

#ifndef GMM_MATRIX_H__
#define GMM_MATRIX_H__

#include "gmm_vector.h"
#include "gmm_sub_vector.h"
#include "gmm_sub_matrix.h"
#include "gmm_transposed.h"

namespace gmm
{

  /* ******************************************************************** */
  /*		                                            		  */
  /*		Identity matrix                         		  */
  /*		                                            		  */
  /* ******************************************************************** */

  struct identity_matrix {
    template <class MAT> void build_with(const MAT &) {}
  };

  template <typename M> inline
  void add(const identity_matrix&, M &v1) {
    size_type n = std::min(gmm::mat_nrows(v1), gmm::mat_ncols(v1));
    for (size_type i = 0; i < n; ++i)
      v1(i,i) += typename linalg_traits<M>::value_type(1);
  }
  template <typename M> inline
  void add(const identity_matrix &I, const M &v1)
  { add(I, linalg_const_cast(v1)); }

  template <typename V1, typename V2> inline
  void mult(const identity_matrix&, const V1 &v1, V2 &v2)
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void mult(const identity_matrix&, const V1 &v1, const V2 &v2) 
  { copy(v1, v2); }
  template <typename V1, typename V2, typename V3> inline
  void mult(const identity_matrix&, const V1 &v1, const V2 &v2, V3 &v3)
  { add(v1, v2, v3); }
  template <typename V1, typename V2, typename V3> inline
  void mult(const identity_matrix&, const V1 &v1, const V2 &v2, const V3 &v3)
  { add(v1, v2, v3); }
  template <typename V1, typename V2> inline
  void left_mult(const identity_matrix&, const V1 &v1, V2 &v2)
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void left_mult(const identity_matrix&, const V1 &v1, const V2 &v2) 
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void right_mult(const identity_matrix&, const V1 &v1, V2 &v2)
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void right_mult(const identity_matrix&, const V1 &v1, const V2 &v2) 
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void transposed_left_mult(const identity_matrix&, const V1 &v1, V2 &v2)
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void transposed_left_mult(const identity_matrix&, const V1 &v1,const V2 &v2) 
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void transposed_right_mult(const identity_matrix&, const V1 &v1, V2 &v2)
  { copy(v1, v2); }
  template <typename V1, typename V2> inline
  void transposed_right_mult(const identity_matrix&,const V1 &v1,const V2 &v2) 
  { copy(v1, v2); }
  template <typename M> void copy_ident(const identity_matrix&, M &m) {
    size_type i = 0, n = std::min(mat_nrows(m), mat_ncols(m));
    clear(m);
    for (; i < n; ++i) m(i,i) = typename linalg_traits<M>::value_type(1);
  }
  template <typename M> inline void copy(const identity_matrix&, M &m)
  { copy_ident(identity_matrix(), m); } 
  template <typename M> inline void copy(const identity_matrix &, const M &m)
  { copy_ident(identity_matrix(), linalg_const_cast(m)); }
  template <typename V1, typename V2> inline
  typename linalg_traits<V1>::value_type
  vect_sp(const identity_matrix &, const V1 &v1, const V2 &v2)
  { return vect_sp(v1, v2); }
  template <typename V1, typename V2> inline
  typename linalg_traits<V1>::value_type
  vect_hp(const identity_matrix &, const V1 &v1, const V2 &v2)
  { return vect_hp(v1, v2); }
  template<typename M> inline bool is_identity(const M&) { return false; }
  inline bool is_identity(const identity_matrix&) { return true; }

  /* ******************************************************************** */
  /*		                                            		  */
  /*		Row matrix                                   		  */
  /*		                                            		  */
  /* ******************************************************************** */

  template<typename V> class row_matrix {
  protected :
    std::vector<V> li; /* array of rows.                                  */
    size_type nc;
    
  public :
    
    typedef typename linalg_traits<V>::reference reference;
    typedef typename linalg_traits<V>::value_type value_type;
    
    row_matrix(size_type r, size_type c) : li(r, V(c)), nc(c) {}
    row_matrix(void) : nc(0) {}
    reference operator ()(size_type l, size_type c) 
    { return li[l][c]; }
    value_type operator ()(size_type l, size_type c) const
    { return li[l][c]; }

    void clear_mat();
    void resize(size_type m, size_type n);

    typename std::vector<V>::iterator begin(void)
    { return li.begin(); }
    typename std::vector<V>::iterator end(void)  
    { return li.end(); }
    typename std::vector<V>::const_iterator begin(void) const
    { return li.begin(); }
    typename std::vector<V>::const_iterator end(void) const
    { return li.end(); }
    
    
    V& row(size_type i) { return li[i]; }
    const V& row(size_type i) const { return li[i]; }
    V& operator[](size_type i) { return li[i]; }
    const V& operator[](size_type i) const { return li[i]; }
    
    inline size_type nrows(void) const { return li.size(); }
    inline size_type ncols(void) const { return nc;        }

    void swap(row_matrix<V> &m) { std::swap(li, m.li); std::swap(nc, m.nc); }
    void swap_row(size_type i, size_type j) { std::swap(li[i], li[j]); }
  };

  template<typename V> void row_matrix<V>::resize(size_type m, size_type n) {
    li.resize(m);
    for (size_type i=0; i < m; ++i) gmm::resize(li[i], n);
    nc = n;
  }


  template<typename V> void row_matrix<V>::clear_mat()
  { for (size_type i=0; i < nrows(); ++i) clear(li[i]); }

  template <typename V> struct linalg_traits<row_matrix<V> > {
    typedef row_matrix<V> this_type;
    typedef this_type origin_type;
    typedef linalg_false is_reference;
    typedef abstract_matrix linalg_type;
    typedef typename linalg_traits<V>::value_type value_type;
    typedef typename linalg_traits<V>::reference reference;
    typedef typename linalg_traits<V>::storage_type storage_type;
    typedef simple_vector_ref<V *> sub_row_type;
    typedef simple_vector_ref<const V *> const_sub_row_type;
    typedef typename std::vector<V>::iterator row_iterator;
    typedef typename std::vector<V>::const_iterator const_row_iterator;
    typedef abstract_null_type sub_col_type;
    typedef abstract_null_type const_sub_col_type;
    typedef abstract_null_type col_iterator;
    typedef abstract_null_type const_col_iterator;
    typedef row_major sub_orientation;
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static row_iterator row_begin(this_type &m) { return m.begin(); }
    static row_iterator row_end(this_type &m) { return m.end(); }
    static const_row_iterator row_begin(const this_type &m)
    { return m.begin(); }
    static const_row_iterator row_end(const this_type &m)
    { return m.end(); }
    static const_sub_row_type row(const const_row_iterator &it)
    { return const_sub_row_type(*it); }
    static sub_row_type row(const row_iterator &it) 
    { return sub_row_type(*it); }
    static origin_type* origin(this_type &m) { return &m; }
    static const origin_type* origin(const this_type &m) { return &m; }
    static void do_clear(this_type &m) { m.clear_mat(); }
    static value_type access(const const_row_iterator &itrow, size_type j)
    { return (*itrow)[j]; }
    static reference access(const row_iterator &itrow, size_type j)
    { return (*itrow)[j]; }
    static void resize(this_type &v, size_type m, size_type n)
    { v.resize(m, n); }
    static void reshape(this_type &, size_type, size_type)
    { GMM_ASSERT1(false, "Sorry, to be done"); }
  };

  template<typename V> std::ostream &operator <<
    (std::ostream &o, const row_matrix<V>& m) { gmm::write(o,m); return o; }

  /* ******************************************************************** */
  /*		                                            		  */
  /*		Column matrix                                		  */
  /*		                                            		  */
  /* ******************************************************************** */

  template<typename V> class col_matrix {
  protected :
    std::vector<V> li; /* array of columns.                               */
    size_type nr;
    
  public :
    
    typedef typename linalg_traits<V>::reference reference;
    typedef typename linalg_traits<V>::value_type value_type;
    
    col_matrix(size_type r, size_type c) : li(c, V(r)), nr(r) { }
    col_matrix(void) : nr(0) {}
    reference operator ()(size_type l, size_type c)
    { return li[c][l]; }
    value_type operator ()(size_type l, size_type c) const
    { return li[c][l]; }

    void clear_mat();
    void resize(size_type, size_type);

    V& col(size_type i) { return li[i]; }
    const V& col(size_type i) const { return li[i]; }
    V& operator[](size_type i) { return li[i]; }
    const V& operator[](size_type i) const { return li[i]; }

    typename std::vector<V>::iterator begin(void)
    { return li.begin(); }
    typename std::vector<V>::iterator end(void)  
    { return li.end(); }
    typename std::vector<V>::const_iterator begin(void) const
    { return li.begin(); }
    typename std::vector<V>::const_iterator end(void) const
    { return li.end(); }
    
    inline size_type ncols(void) const { return li.size(); }
    inline size_type nrows(void) const { return nr; }

    void swap(col_matrix<V> &m) { std::swap(li, m.li); std::swap(nr, m.nr); }
    void swap_col(size_type i, size_type j) { std::swap(li[i], li[j]); }
  };

  template<typename V> void col_matrix<V>::resize(size_type m, size_type n) {
    li.resize(n);
    for (size_type i=0; i < n; ++i) gmm::resize(li[i], m);
    nr = m;
  }

  template<typename V> void col_matrix<V>::clear_mat()
  { for (size_type i=0; i < ncols(); ++i)  clear(li[i]); }

  template <typename V> struct linalg_traits<col_matrix<V> > {
    typedef col_matrix<V> this_type;
    typedef this_type origin_type;
    typedef linalg_false is_reference;
    typedef abstract_matrix linalg_type;
    typedef typename linalg_traits<V>::value_type value_type;
    typedef typename linalg_traits<V>::reference reference;
    typedef typename linalg_traits<V>::storage_type storage_type;
    typedef simple_vector_ref<V *> sub_col_type;
    typedef simple_vector_ref<const V *> const_sub_col_type;
    typedef typename std::vector<V>::iterator col_iterator;
    typedef typename std::vector<V>::const_iterator const_col_iterator;
    typedef abstract_null_type sub_row_type;
    typedef abstract_null_type const_sub_row_type;
    typedef abstract_null_type row_iterator;
    typedef abstract_null_type const_row_iterator;
    typedef col_major sub_orientation;
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static col_iterator col_begin(this_type &m) { return m.begin(); }
    static col_iterator col_end(this_type &m) { return m.end(); }
    static const_col_iterator col_begin(const this_type &m)
    { return m.begin(); }
    static const_col_iterator col_end(const this_type &m)
    { return m.end(); }
    static const_sub_col_type col(const const_col_iterator &it)
    { return const_sub_col_type(*it); }
    static sub_col_type col(const col_iterator &it) 
    { return sub_col_type(*it); }
    static origin_type* origin(this_type &m) { return &m; }
    static const origin_type* origin(const this_type &m) { return &m; }
    static void do_clear(this_type &m) { m.clear_mat(); }
    static value_type access(const const_col_iterator &itcol, size_type j)
    { return (*itcol)[j]; }
    static reference access(const col_iterator &itcol, size_type j)
    { return (*itcol)[j]; }
    static void resize(this_type &v, size_type m, size_type n)
    { v.resize(m,n); }
    static void reshape(this_type &, size_type, size_type)
    { GMM_ASSERT1(false, "Sorry, to be done"); }
  };

  template<typename V> std::ostream &operator <<
    (std::ostream &o, const col_matrix<V>& m) { gmm::write(o,m); return o; }

  /* ******************************************************************** */
  /*		                                            		  */
  /*		Dense matrix                                		  */
  /*		                                            		  */
  /* ******************************************************************** */

  template<typename T> class dense_matrix : public std::vector<T> {
  public:
    typedef typename std::vector<T>::size_type size_type;
    typedef typename std::vector<T>::iterator iterator;
    typedef typename std::vector<T>::const_iterator const_iterator;
    
  protected:
    size_type nbc, nbl;
    
  public:
    
    inline const T& operator ()(size_type l, size_type c) const {
      GMM_ASSERT2(l < nbl && c < nbc, "out of range");
      return *(this->begin() + c*nbl+l);
    }
    inline T& operator ()(size_type l, size_type c) {
      GMM_ASSERT2(l < nbl && c < nbc, "out of range");
      return *(this->begin() + c*nbl+l);
    }

    void resize(size_type, size_type);
    void reshape(size_type, size_type);
    
    void fill(T a, T b = T(0));
    inline size_type nrows(void) const { return nbl; }
    inline size_type ncols(void) const { return nbc; }
    void swap(dense_matrix<T> &m)
    { std::vector<T>::swap(m); std::swap(nbc, m.nbc); std::swap(nbl, m.nbl); }
    
    dense_matrix(size_type l, size_type c)
      : std::vector<T>(c*l), nbc(c), nbl(l)  {}
    dense_matrix(void) { nbl = nbc = 0; }
  };

  template<typename T> void dense_matrix<T>::reshape(size_type m,size_type n) {
    GMM_ASSERT2(n*m == nbl*nbc, "dimensions mismatch");
    nbl = m; nbc = n;
  }

  template<typename T> void dense_matrix<T>::resize(size_type m, size_type n) {
    if (n*m > nbc*nbl) std::vector<T>::resize(n*m);
    if (m < nbl) {
      for (size_type i = 1; i < std::min(nbc, n); ++i)
	std::copy(this->begin()+i*nbl, this->begin()+(i*nbl+m),
		  this->begin()+i*m);
      for (size_type i = std::min(nbc, n); i < n; ++i)
	std::fill(this->begin()+(i*m), this->begin()+(i+1)*m, T(0));
      }
    else if (m > nbl) { /* do nothing when the nb of rows does not change */
      for (size_type i = std::min(nbc, n); i > 1; --i)
	std::copy(this->begin()+(i-1)*nbl, this->begin()+i*nbl,
		  this->begin()+(i-1)*m);
      for (size_type i = 0; i < std::min(nbc, n); ++i)
	std::fill(this->begin()+(i*m+nbl), this->begin()+(i+1)*m, T(0));
    }
    if (n*m < nbc*nbl) std::vector<T>::resize(n*m);
    nbl = m; nbc = n;
  }
  
  template<typename T> void dense_matrix<T>::fill(T a, T b) {
    std::fill(this->begin(), this->end(), b);
    size_type n = std::min(nbl, nbc);
    if (a != b) for (size_type i = 0; i < n; ++i) (*this)(i,i) = a; 
  }

  template <typename T> struct linalg_traits<dense_matrix<T> > {
    typedef dense_matrix<T> this_type;
    typedef this_type origin_type;
    typedef linalg_false is_reference;
    typedef abstract_matrix linalg_type;
    typedef T value_type;
    typedef T& reference;
    typedef abstract_dense storage_type;
    typedef tab_ref_reg_spaced_with_origin<typename this_type::iterator,
					   this_type> sub_row_type;
    typedef tab_ref_reg_spaced_with_origin<typename this_type::const_iterator,
					   this_type> const_sub_row_type;
    typedef dense_compressed_iterator<typename this_type::iterator,
				      typename this_type::iterator,
				      this_type *> row_iterator;
    typedef dense_compressed_iterator<typename this_type::const_iterator,
				      typename this_type::iterator,
				      const this_type *> const_row_iterator;
    typedef tab_ref_with_origin<typename this_type::iterator, 
				this_type> sub_col_type;
    typedef tab_ref_with_origin<typename this_type::const_iterator,
				this_type> const_sub_col_type;
    typedef dense_compressed_iterator<typename this_type::iterator,
				      typename this_type::iterator,
				      this_type *> col_iterator;
    typedef dense_compressed_iterator<typename this_type::const_iterator,
				      typename this_type::iterator,
				      const this_type *> const_col_iterator;
    typedef col_and_row sub_orientation;
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static const_sub_row_type row(const const_row_iterator &it)
    { return const_sub_row_type(*it, it.nrows, it.ncols, it.origin); }
    static const_sub_col_type col(const const_col_iterator &it)
    { return const_sub_col_type(*it, *it + it.nrows, it.origin); }
    static sub_row_type row(const row_iterator &it)
    { return sub_row_type(*it, it.nrows, it.ncols, it.origin); }
    static sub_col_type col(const col_iterator &it)
    { return sub_col_type(*it, *it + it.nrows, it.origin); }
    static row_iterator row_begin(this_type &m)
    { return row_iterator(m.begin(), m.size() ? 1 : 0, m.nrows(), m.ncols(), 0, &m); }
    static row_iterator row_end(this_type &m)
    { return row_iterator(m.begin(), m.size() ? 1 : 0, m.nrows(), m.ncols(), m.nrows(), &m); }
    static const_row_iterator row_begin(const this_type &m)
    { return const_row_iterator(m.begin(), m.size() ? 1 : 0, m.nrows(), m.ncols(), 0, &m); }
    static const_row_iterator row_end(const this_type &m)
    { return const_row_iterator(m.begin(),  m.size() ? 1 : 0, m.nrows(), m.ncols(), m.nrows(), &m); }
    static col_iterator col_begin(this_type &m)
    { return col_iterator(m.begin(), m.nrows(), m.nrows(), m.ncols(), 0, &m); }
    static col_iterator col_end(this_type &m)
    { return col_iterator(m.begin(), m.nrows(), m.nrows(), m.ncols(), m.ncols(), &m); }
    static const_col_iterator col_begin(const this_type &m)
    { return const_col_iterator(m.begin(), m.nrows(), m.nrows(), m.ncols(), 0, &m); }
    static const_col_iterator col_end(const this_type &m)
    { return const_col_iterator(m.begin(),m.nrows(),m.nrows(),m.ncols(),m.ncols(), &m); }
    static origin_type* origin(this_type &m) { return &m; }
    static const origin_type* origin(const this_type &m) { return &m; }
    static void do_clear(this_type &m) { m.fill(value_type(0)); }
    static value_type access(const const_col_iterator &itcol, size_type j)
    { return (*itcol)[j]; }
    static reference access(const col_iterator &itcol, size_type j)
    { return (*itcol)[j]; }
    static void resize(this_type &v, size_type m, size_type n)
    { v.resize(m,n); }
    static void reshape(this_type &v, size_type m, size_type n)
    { v.reshape(m, n); }
  };

  template<typename T> std::ostream &operator <<
    (std::ostream &o, const dense_matrix<T>& m) { gmm::write(o,m); return o; }

  /* ******************************************************************** */
  /*                                                                      */
  /*	        Read only compressed sparse column matrix                 */
  /*                                                                      */
  /* ******************************************************************** */

  template <typename T, int shift = 0>
  struct csc_matrix {
    typedef unsigned int IND_TYPE;

    T *pr;        // values.
    IND_TYPE *ir; // row indices.
    IND_TYPE *jc; // column repartition on pr and ir.
    size_type nc, nr;

    typedef T value_type;
    typedef T& access_type;

    template <typename Matrix> void init_with_good_format(const Matrix &B);
    template <typename Matrix> void init_with(const Matrix &A);
    void init_with(const col_matrix<gmm::rsvector<T> > &B)
    { init_with_good_format(B); }
    void init_with(const col_matrix<wsvector<T> > &B)
    { init_with_good_format(B); }
    template <typename PT1, typename PT2, typename PT3, int cshift>
    void init_with(const csc_matrix_ref<PT1,PT2,PT3,cshift>& B)
    { init_with_good_format(B); }
    template <typename U, int cshift>    
    void init_with(const csc_matrix<U, cshift>& B)
    { init_with_good_format(B); }

    void init_with_identity(size_type n);

    csc_matrix(void) : pr(0), ir(0), jc(0), nc(0), nr(0) {}
    csc_matrix(size_type nnr, size_type nnc);
    ~csc_matrix() { if (pr) { delete[] pr; delete[] ir; delete[] jc; } }

    size_type nrows(void) const { return nr; }
    size_type ncols(void) const { return nc; }
    void swap(csc_matrix<T, shift> &m) { 
      std::swap(pr, m.pr); 
      std::swap(ir,m.ir); std::swap(jc, m.jc); 
      std::swap(nc, m.nc); std::swap(nr,m.nr);
    }
    value_type operator()(size_type i, size_type j) const
    { return mat_col(*this, j)[i]; }
  };

  template <typename T, int shift> template<typename Matrix>
  void csc_matrix<T, shift>::init_with_good_format(const Matrix &B) {
    typedef typename linalg_traits<Matrix>::const_sub_col_type col_type;
    if (pr) { delete[] pr; delete[] ir; delete[] jc; }
    nc = mat_ncols(B); nr = mat_nrows(B);
    jc = new IND_TYPE[nc+1];
    jc[0] = shift;
    for (size_type j = 0; j < nc; ++j) {
      jc[j+1] = jc[j] + nnz(mat_const_col(B, j));
    }
    pr = new T[jc[nc]];
    ir = new IND_TYPE[jc[nc]];
    for (size_type j = 0; j < nc; ++j) {
      col_type col = mat_const_col(B, j);
      typename linalg_traits<col_type>::const_iterator
	it = vect_const_begin(col), ite = vect_const_end(col);
      for (size_type k = 0; it != ite; ++it, ++k)
	{ pr[jc[j]-shift+k] = *it; ir[jc[j]-shift+k] = it.index() + shift; }
    }
  }
  
  template <typename T, int shift> template <typename Matrix>
  void csc_matrix<T, shift>::init_with(const Matrix &A) {
    col_matrix<wsvector<T> > B(mat_nrows(A), mat_ncols(A));
    copy(A, B);
    init_with_good_format(B);
  }
  
  template <typename T, int shift>
  void csc_matrix<T, shift>::init_with_identity(size_type n) {
    if (pr) { delete[] pr; delete[] ir; delete[] jc; }
    nc = nr = n; 
    pr = new T[nc];
    ir = new IND_TYPE[nc];
    jc = new IND_TYPE[nc+1];
    for (size_type j = 0; j < nc; ++j)
      { ir[j] = jc[j] = shift + j; pr[j] = T(1); }
    jc[nc] = shift + nc;
  }
  
  template <typename T, int shift>
  csc_matrix<T, shift>::csc_matrix(size_type nnr, size_type nnc)
    : nc(nnc), nr(nnr) {
    pr = new T[1];  ir = new IND_TYPE[1];
    jc = new IND_TYPE[nc+1];
    for (size_type j = 0; j <= nc; ++j) jc[j] = shift;
  }

  template <typename T, int shift>
  struct linalg_traits<csc_matrix<T, shift> > {
    typedef csc_matrix<T, shift> this_type;
    typedef typename this_type::IND_TYPE IND_TYPE;
    typedef linalg_const is_reference;
    typedef abstract_matrix linalg_type;
    typedef T value_type;
    typedef T origin_type;
    typedef T reference;
    typedef abstract_sparse storage_type;
    typedef abstract_null_type sub_row_type;
    typedef abstract_null_type const_sub_row_type;
    typedef abstract_null_type row_iterator;
    typedef abstract_null_type const_row_iterator;
    typedef abstract_null_type sub_col_type;
    typedef cs_vector_ref<const T *, const IND_TYPE *, shift>
    const_sub_col_type;
    typedef sparse_compressed_iterator<const T *, const IND_TYPE *,
				       const IND_TYPE *, shift>
    const_col_iterator;
    typedef abstract_null_type col_iterator;
    typedef col_major sub_orientation;
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static const_col_iterator col_begin(const this_type &m)
    { return const_col_iterator(m.pr, m.ir, m.jc, m.nr, m.pr); }
    static const_col_iterator col_end(const this_type &m)
    { return const_col_iterator(m.pr, m.ir, m.jc + m.nc, m.nr, m.pr); }
    static const_sub_col_type col(const const_col_iterator &it) {
      return const_sub_col_type(it.pr + *(it.jc) - shift,
				it.ir + *(it.jc) - shift,
				*(it.jc + 1) - *(it.jc), it.n);
    }
    static const origin_type* origin(const this_type &m) { return m.pr; }
    static void do_clear(this_type &m) { m.do_clear(); }
    static value_type access(const const_col_iterator &itcol, size_type j)
    { return col(itcol)[j]; }
  };

  template <typename T, int shift>
  std::ostream &operator <<
    (std::ostream &o, const csc_matrix<T, shift>& m)
  { gmm::write(o,m); return o; }
  
  template <typename T, int shift>
  inline void copy(const identity_matrix &, csc_matrix<T, shift>& M)
  { M.init_with_identity(mat_nrows(M)); }

  template <typename Matrix, typename T, int shift>
  inline void copy(const Matrix &A, csc_matrix<T, shift>& M)
  { M.init_with(A); }

  /* ******************************************************************** */
  /*                                                                      */
  /*	        Read only compressed sparse row matrix                    */
  /*                                                                      */
  /* ******************************************************************** */

  template <typename T, int shift = 0>
  struct csr_matrix {

    typedef unsigned int IND_TYPE;

    T *pr;        // values.
    IND_TYPE *ir; // col indices.
    IND_TYPE *jc; // row repartition on pr and ir.
    size_type nc, nr;

    typedef T value_type;
    typedef T& access_type;


    template <typename Matrix> void init_with_good_format(const Matrix &B);
    void init_with(const row_matrix<wsvector<T> > &B)
    { init_with_good_format(B); }
    void init_with(const row_matrix<rsvector<T> > &B)
    { init_with_good_format(B); }
    template <typename PT1, typename PT2, typename PT3, int cshift>
    void init_with(const csr_matrix_ref<PT1,PT2,PT3,cshift>& B)
    { init_with_good_format(B); }
    template <typename U, int cshift>
    void init_with(const csr_matrix<U, cshift>& B)
    { init_with_good_format(B); }

    template <typename Matrix> void init_with(const Matrix &A);
    void init_with_identity(size_type n);

    csr_matrix(void) : pr(0), ir(0), jc(0), nc(0), nr(0) {}
    csr_matrix(size_type nnr, size_type nnc);
    ~csr_matrix() { if (pr) { delete[] pr; delete[] ir; delete[] jc; } }

    size_type nrows(void) const { return nr; }
    size_type ncols(void) const { return nc; }
    void swap(csr_matrix<T, shift> &m) { 
      std::swap(pr, m.pr); 
      std::swap(ir,m.ir); std::swap(jc, m.jc); 
      std::swap(nc, m.nc); std::swap(nr,m.nr);
    }
   
    value_type operator()(size_type i, size_type j) const
    { return mat_row(*this, i)[j]; }
  };
  
  template <typename T, int shift> template <typename Matrix>
  void csr_matrix<T, shift>::init_with_good_format(const Matrix &B) {
    typedef typename linalg_traits<Matrix>::const_sub_row_type row_type;
    if (pr) { delete[] pr; delete[] ir; delete[] jc; }
    nc = mat_ncols(B); nr = mat_nrows(B);
    jc = new IND_TYPE[nr+1];
    jc[0] = shift;
    for (size_type j = 0; j < nr; ++j) {
      jc[j+1] = jc[j] + nnz(mat_const_row(B, j));
    }
    pr = new T[jc[nr]];
    ir = new IND_TYPE[jc[nr]];
    for (size_type j = 0; j < nr; ++j) {
      row_type row = mat_const_row(B, j);
      typename linalg_traits<row_type>::const_iterator
	it = vect_const_begin(row), ite = vect_const_end(row);
      for (size_type k = 0; it != ite; ++it, ++k)
	{ pr[jc[j]-shift+k] = *it; ir[jc[j]-shift+k] = it.index()+shift; }
    }
  }

  template <typename T, int shift> template <typename Matrix> 
  void csr_matrix<T, shift>::init_with(const Matrix &A) { 
    row_matrix<wsvector<T> > B(mat_nrows(A), mat_ncols(A)); 
    copy(A, B); 
    init_with_good_format(B);
  }

  template <typename T, int shift> 
  void csr_matrix<T, shift>::init_with_identity(size_type n) {
    if (pr) { delete[] pr; delete[] ir; delete[] jc; }
    nc = nr = n; 
    pr = new T[nr];
    ir = new IND_TYPE[nr];
    jc = new IND_TYPE[nr+1];
    for (size_type j = 0; j < nr; ++j)
      { ir[j] = jc[j] = shift + j; pr[j] = T(1); }
    jc[nr] = shift + nr;
  }

  template <typename T, int shift>
  csr_matrix<T, shift>::csr_matrix(size_type nnr, size_type nnc)
    : nc(nnc), nr(nnr) {
    pr = new T[1];  ir = new IND_TYPE[1];
    jc = new IND_TYPE[nr+1];
    for (size_type j = 0; j < nr; ++j) jc[j] = shift;
    jc[nr] = shift;
  }


  template <typename T, int shift>
  struct linalg_traits<csr_matrix<T, shift> > {
    typedef csr_matrix<T, shift> this_type;
    typedef typename this_type::IND_TYPE IND_TYPE;
    typedef linalg_const is_reference;
    typedef abstract_matrix linalg_type;
    typedef T value_type;
    typedef T origin_type;
    typedef T reference;
    typedef abstract_sparse storage_type;
    typedef abstract_null_type sub_col_type;
    typedef abstract_null_type const_sub_col_type;
    typedef abstract_null_type col_iterator;
    typedef abstract_null_type const_col_iterator;
    typedef abstract_null_type sub_row_type;
    typedef cs_vector_ref<const T *, const IND_TYPE *, shift>
    const_sub_row_type;
    typedef sparse_compressed_iterator<const T *, const IND_TYPE *,
				       const IND_TYPE *, shift>
    const_row_iterator;
    typedef abstract_null_type row_iterator;
    typedef row_major sub_orientation;
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static const_row_iterator row_begin(const this_type &m)
    { return const_row_iterator(m.pr, m.ir, m.jc, m.nc, m.pr); }
    static const_row_iterator row_end(const this_type &m)
    { return const_row_iterator(m.pr, m.ir, m.jc + m.nr, m.nc, m.pr); }
    static const_sub_row_type row(const const_row_iterator &it) {
      return const_sub_row_type(it.pr + *(it.jc) - shift,
				it.ir + *(it.jc) - shift,
				*(it.jc + 1) - *(it.jc), it.n);
    }
    static const origin_type* origin(const this_type &m) { return m.pr; }
    static void do_clear(this_type &m) { m.do_clear(); }
    static value_type access(const const_row_iterator &itrow, size_type j)
    { return row(itrow)[j]; }
  };

  template <typename T, int shift>
  std::ostream &operator <<
    (std::ostream &o, const csr_matrix<T, shift>& m)
  { gmm::write(o,m); return o; }
  
  template <typename T, int shift>
  inline void copy(const identity_matrix &, csr_matrix<T, shift>& M)
  { M.init_with_identity(mat_nrows(M)); }

  template <typename Matrix, typename T, int shift>
  inline void copy(const Matrix &A, csr_matrix<T, shift>& M)
  { M.init_with(A); }

  /* ******************************************************************** */
  /*		                                            		  */
  /*		Block matrix                                		  */
  /*		                                            		  */
  /* ******************************************************************** */

  template <typename MAT> class block_matrix {
  protected :
    std::vector<MAT> blocks;
    size_type nrowblocks_;
    size_type ncolblocks_;
    std::vector<sub_interval> introw, intcol;

  public :
    typedef typename linalg_traits<MAT>::value_type value_type;
    typedef typename linalg_traits<MAT>::reference reference;

    size_type nrows(void) const { return introw[nrowblocks_-1].max; }
    size_type ncols(void) const { return intcol[ncolblocks_-1].max; }
    size_type nrowblocks(void) const { return nrowblocks_; }
    size_type ncolblocks(void) const { return ncolblocks_; }
    const sub_interval &subrowinterval(size_type i) const { return introw[i]; }
    const sub_interval &subcolinterval(size_type i) const { return intcol[i]; }
    const MAT &block(size_type i, size_type j) const 
    { return blocks[j*ncolblocks_+i]; }
    MAT &block(size_type i, size_type j)
    { return blocks[j*ncolblocks_+i]; }
    void do_clear(void);
    // to be done : read and write access to a component
    value_type operator() (size_type i, size_type j) const {
      size_type k, l;
      for (k = 0; k < nrowblocks_; ++k)
	if (i >= introw[k].min && i <  introw[k].max) break;
      for (l = 0; l < nrowblocks_; ++l)
	if (j >= introw[l].min && j <  introw[l].max) break;
      return (block(k, l))(i - introw[k].min, j - introw[l].min);
    }
    reference operator() (size_type i, size_type j) {
      size_type k, l;
      for (k = 0; k < nrowblocks_; ++k)
	if (i >= introw[k].min && i <  introw[k].max) break;
      for (l = 0; l < nrowblocks_; ++l)
	if (j >= introw[l].min && j <  introw[l].max) break;
      return (block(k, l))(i - introw[k].min, j - introw[l].min);
    }
    
    template <typename CONT> void resize(const CONT &c1, const CONT &c2);
    template <typename CONT> block_matrix(const CONT &c1, const CONT &c2)
    { resize(c1, c2); }
    block_matrix(void) {}

  };

  template <typename MAT> struct linalg_traits<block_matrix<MAT> > {
    typedef block_matrix<MAT> this_type;
    typedef linalg_false is_reference;
    typedef abstract_matrix linalg_type;
    typedef this_type origin_type;
    typedef typename linalg_traits<MAT>::value_type value_type;
    typedef typename linalg_traits<MAT>::reference reference;
    typedef typename linalg_traits<MAT>::storage_type storage_type;
    typedef abstract_null_type sub_row_type;       // to be done ...
    typedef abstract_null_type const_sub_row_type; // to be done ...
    typedef abstract_null_type row_iterator;       // to be done ...
    typedef abstract_null_type const_row_iterator; // to be done ...
    typedef abstract_null_type sub_col_type;       // to be done ...
    typedef abstract_null_type const_sub_col_type; // to be done ...
    typedef abstract_null_type col_iterator;       // to be done ...
    typedef abstract_null_type const_col_iterator; // to be done ...
    typedef abstract_null_type sub_orientation;    // to be done ...
    typedef linalg_true index_sorted;
    static size_type nrows(const this_type &m) { return m.nrows(); }
    static size_type ncols(const this_type &m) { return m.ncols(); }
    static origin_type* origin(this_type &m) { return &m; }
    static const origin_type* origin(const this_type &m) { return &m; }
    static void do_clear(this_type &m) { m.do_clear(); }
    // access to be done ...    
    static void resize(this_type &, size_type , size_type)
    { GMM_ASSERT1(false, "Sorry, to be done"); }
    static void reshape(this_type &, size_type , size_type)
    { GMM_ASSERT1(false, "Sorry, to be done"); }
  };

  template <typename MAT> void block_matrix<MAT>::do_clear(void) { 
    for (size_type j = 0, l = 0; j < ncolblocks_; ++j)
      for (size_type i = 0, k = 0; i < nrowblocks_; ++i)
	clear(block(i,j));
  }

  template <typename MAT> template <typename CONT>
  void block_matrix<MAT>::resize(const CONT &c1, const CONT &c2) {
    nrowblocks_ = c1.size(); ncolblocks_ = c2.size();
    blocks.resize(nrowblocks_ * ncolblocks_);
    intcol.resize(ncolblocks_);
    introw.resize(nrowblocks_);
    for (size_type j = 0, l = 0; j < ncolblocks_; ++j) {
      intcol[j] = sub_interval(l, c2[j]); l += c2[j];
      for (size_type i = 0, k = 0; i < nrowblocks_; ++i) {
	if (j == 0) { introw[i] = sub_interval(k, c1[i]); k += c1[i]; }
	block(i, j) = MAT(c1[i], c2[j]);
      }
    }
  }

  template <typename M1, typename M2>
  void copy(const block_matrix<M1> &m1, M2 &m2) {
    for (size_type j = 0; j < m1.ncolblocks(); ++j)
      for (size_type i = 0; i < m1.nrowblocks(); ++i)
	copy(m1.block(i,j), sub_matrix(m2, m1.subrowinterval(i), 
				       m1.subcolinterval(j)));
  }

  template <typename M1, typename M2>
  void copy(const block_matrix<M1> &m1, const M2 &m2)
  { copy(m1, linalg_const_cast(m2)); }
  

  template <typename MAT, typename V1, typename V2>
  void mult(const block_matrix<MAT> &m, const V1 &v1, V2 &v2) {
    clear(v2);
    typename sub_vector_type<V2 *, sub_interval>::vector_type sv;
    for (size_type i = 0; i < m.nrowblocks() ; ++i)
      for (size_type j = 0; j < m.ncolblocks() ; ++j) {
	sv = sub_vector(v2, m.subrowinterval(i));
	mult(m.block(i,j),
	     sub_vector(v1, m.subcolinterval(j)), sv, sv);
      }
  }

  template <typename MAT, typename V1, typename V2, typename V3>
  void mult(const block_matrix<MAT> &m, const V1 &v1, const V2 &v2, V3 &v3) {
    typename sub_vector_type<V3 *, sub_interval>::vector_type sv;
    for (size_type i = 0; i < m.nrowblocks() ; ++i)
      for (size_type j = 0; j < m.ncolblocks() ; ++j) {
	sv = sub_vector(v3, m.subrowinterval(i));
	if (j == 0)
	  mult(m.block(i,j),
	       sub_vector(v1, m.subcolinterval(j)),
	       sub_vector(v2, m.subrowinterval(i)), sv);
	else
	  mult(m.block(i,j),
	       sub_vector(v1, m.subcolinterval(j)), sv, sv);
      }
    
  }

  template <typename MAT, typename V1, typename V2>
  void mult(const block_matrix<MAT> &m, const V1 &v1, const V2 &v2)
  { mult(m, v1, linalg_const_cast(v2)); }

  template <typename MAT, typename V1, typename V2, typename V3>
  void mult(const block_matrix<MAT> &m, const V1 &v1, const V2 &v2, 
	    const V3 &v3)
  { mult_const(m, v1, v2, linalg_const_cast(v3)); }

}
  /* ******************************************************************** */
  /*		                                            		  */
  /*		Distributed matrices                                	  */
  /*		                                            		  */
  /* ******************************************************************** */

#ifdef GMM_USES_MPI
#include <mpi.h>
 
namespace gmm { 
  
  template <typename T> inline MPI_Datatype mpi_type(T)
  { GMM_ASSERT1(false, "Sorry unsupported type"); return MPI_FLOAT; }
  inline MPI_Datatype mpi_type(double) { return MPI_DOUBLE; }
  inline MPI_Datatype mpi_type(float) { return MPI_FLOAT; }
  inline MPI_Datatype mpi_type(long double) { return MPI_LONG_DOUBLE; }
#ifndef LAM_MPI
  inline MPI_Datatype mpi_type(std::complex<float>) { return MPI_COMPLEX; }
  inline MPI_Datatype mpi_type(std::complex<double>) { return MPI_DOUBLE_COMPLEX; }
#endif
  inline MPI_Datatype mpi_type(int) { return MPI_INT; }
  inline MPI_Datatype mpi_type(unsigned int) { return MPI_UNSIGNED; }
  inline MPI_Datatype mpi_type(size_t) {
    if (sizeof(int) == sizeof(size_t)) return MPI_UNSIGNED;
    if (sizeof(long) == sizeof(size_t)) return MPI_UNSIGNED_LONG;
    return MPI_LONG_LONG;
  }



  template <typename MAT> struct mpi_distributed_matrix {
    MAT M;

    mpi_distributed_matrix(size_type n, size_type m) : M(n, m) {}
    mpi_distributed_matrix() {}

    const MAT &local_matrix(void) const { return M; }
    MAT &local_matrix(void) { return M; }
  };
  
  template <typename MAT> inline MAT &eff_matrix(MAT &m) { return m; }
  template <typename MAT> inline
  const MAT &eff_matrix(const MAT &m) { return m; }
  template <typename MAT> inline
  MAT &eff_matrix(mpi_distributed_matrix<MAT> &m) { return m.M; }
  template <typename MAT> inline
  const MAT &eff_matrix(const mpi_distributed_matrix<MAT> &m) { return m.M; }
  

  template <typename MAT1, typename MAT2>
  inline void copy(const mpi_distributed_matrix<MAT1> &m1,
		   mpi_distributed_matrix<MAT2> &m2)
  { copy(eff_matrix(m1), eff_matrix(m2)); }
  template <typename MAT1, typename MAT2>
  inline void copy(const mpi_distributed_matrix<MAT1> &m1,
		   const mpi_distributed_matrix<MAT2> &m2)
  { copy(m1.M, m2.M); }
  
  template <typename MAT1, typename MAT2>
  inline void copy(const mpi_distributed_matrix<MAT1> &m1, MAT2 &m2)
  { copy(m1.M, m2); }
  template <typename MAT1, typename MAT2>
  inline void copy(const mpi_distributed_matrix<MAT1> &m1, const MAT2 &m2)
  { copy(m1.M, m2); }
  

  template <typename MATSP, typename V1, typename V2> inline
  typename strongest_value_type3<V1,V2,MATSP>::value_type
  vect_sp(const mpi_distributed_matrix<MATSP> &ps, const V1 &v1,
	  const V2 &v2) {
    typedef typename strongest_value_type3<V1,V2,MATSP>::value_type T;
    T res = vect_sp(ps.M, v1, v2), rest;
    MPI_Allreduce(&res, &rest, 1, mpi_type(T()), MPI_SUM,MPI_COMM_WORLD);
    return rest;
  }

  template <typename MAT, typename V1, typename V2>
  inline void mult_add(const mpi_distributed_matrix<MAT> &m, const V1 &v1,
		       V2 &v2) {
    typedef typename linalg_traits<V2>::value_type T;
    std::vector<T> v3(vect_size(v2)), v4(vect_size(v2));
    static double tmult_tot = 0.0;
    static double tmult_tot2 = 0.0;
    double t_ref = MPI_Wtime();
    gmm::mult(m.M, v1, v3);
    if (is_sparse(v2)) GMM_WARNING2("Using a plain temporary, here.");
    double t_ref2 = MPI_Wtime();
    MPI_Allreduce(&(v3[0]), &(v4[0]),gmm::vect_size(v2), mpi_type(T()),
		  MPI_SUM,MPI_COMM_WORLD);
    tmult_tot2 = MPI_Wtime()-t_ref2;
    cout << "reduce mult mpi = " << tmult_tot2 << endl;
    gmm::add(v4, v2);
    tmult_tot = MPI_Wtime()-t_ref;
    cout << "tmult mpi = " << tmult_tot << endl;
  }

  template <typename MAT, typename V1, typename V2>
  void mult_add(const mpi_distributed_matrix<MAT> &m, const V1 &v1,
		const V2 &v2_)
  { mult_add(m, v1, const_cast<V2 &>(v2_)); }

  template <typename MAT, typename V1, typename V2>
  inline void mult(const mpi_distributed_matrix<MAT> &m, const V1 &v1,
		   const V2 &v2_)
  { V2 &v2 = const_cast<V2 &>(v2_); clear(v2); mult_add(m, v1, v2); }

  template <typename MAT, typename V1, typename V2>
  inline void mult(const mpi_distributed_matrix<MAT> &m, const V1 &v1,
		   V2 &v2)
  { clear(v2); mult_add(m, v1, v2); }

  template <typename MAT, typename V1, typename V2, typename V3>
  inline void mult(const mpi_distributed_matrix<MAT> &m, const V1 &v1,
		   const V2 &v2, const V3 &v3_)
  { V3 &v3 = const_cast<V3 &>(v3_); gmm::copy(v2, v3); mult_add(m, v1, v3); }

  template <typename MAT, typename V1, typename V2, typename V3>
  inline void mult(const mpi_distributed_matrix<MAT> &m, const V1 &v1,
		   const V2 &v2, V3 &v3)
  { gmm::copy(v2, v3); mult_add(m, v1, v3); }
  

  template <typename MAT> inline
  size_type mat_nrows(const mpi_distributed_matrix<MAT> &M) 
  { return mat_nrows(M.M); }
  template <typename MAT> inline
  size_type mat_ncols(const mpi_distributed_matrix<MAT> &M) 
  { return mat_nrows(M.M); }
  template <typename MAT> inline
  void resize(mpi_distributed_matrix<MAT> &M, size_type m, size_type n)
  { resize(M.M, m, n); }
  template <typename MAT> inline void clear(mpi_distributed_matrix<MAT> &M)
  { clear(M.M); }
  

  // For compute reduced system
  template <typename MAT1, typename MAT2> inline
  void mult(const MAT1 &M1, const mpi_distributed_matrix<MAT2> &M2,
	    mpi_distributed_matrix<MAT2> &M3)
  { mult(M1, M2.M, M3.M); }
  template <typename MAT1, typename MAT2> inline
  void mult(const mpi_distributed_matrix<MAT2> &M2,
	    const MAT1 &M1, mpi_distributed_matrix<MAT2> &M3)
  { mult(M2.M, M1, M3.M); }
  template <typename MAT1, typename MAT2, typename MAT3> inline
  void mult(const MAT1 &M1, const mpi_distributed_matrix<MAT2> &M2,
		   MAT3 &M3)
  { mult(M1, M2.M, M3); }
  template <typename MAT1, typename MAT2, typename MAT3> inline
  void mult(const MAT1 &M1, const mpi_distributed_matrix<MAT2> &M2,
		   const MAT3 &M3)
  { mult(M1, M2.M, M3); }

  template <typename M, typename SUBI1, typename SUBI2>
  struct sub_matrix_type<const mpi_distributed_matrix<M> *, SUBI1, SUBI2>
  { typedef abstract_null_type matrix_type; };

  template <typename M, typename SUBI1, typename SUBI2>
  struct sub_matrix_type<mpi_distributed_matrix<M> *, SUBI1, SUBI2>
  { typedef abstract_null_type matrix_type; };

  template <typename M, typename SUBI1, typename SUBI2>  inline
  typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI2>
  ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI2>::matrix_type,
   M *>::return_type
   sub_matrix(mpi_distributed_matrix<M> &m, const SUBI1 &si1, const SUBI2 &si2)
  { return sub_matrix(m.M, si1, si2); }

  template <typename MAT, typename SUBI1, typename SUBI2>  inline
  typename select_return<typename sub_matrix_type<const MAT *, SUBI1, SUBI2>
  ::matrix_type, typename sub_matrix_type<MAT *, SUBI1, SUBI2>::matrix_type,
			 const MAT *>::return_type
  sub_matrix(const mpi_distributed_matrix<MAT> &m, const SUBI1 &si1,
	     const SUBI2 &si2)
  { return sub_matrix(m.M, si1, si2);  }

  template <typename M, typename SUBI1>  inline
    typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI1>
    ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI1>::matrix_type,
    M *>::return_type
  sub_matrix(mpi_distributed_matrix<M> &m, const SUBI1 &si1) 
  { return sub_matrix(m.M, si1, si1); }

  template <typename M, typename SUBI1>  inline
    typename select_return<typename sub_matrix_type<const M *, SUBI1, SUBI1>
    ::matrix_type, typename sub_matrix_type<M *, SUBI1, SUBI1>::matrix_type,
    const M *>::return_type
  sub_matrix(const mpi_distributed_matrix<M> &m, const SUBI1 &si1)
  { return sub_matrix(m.M, si1, si1); }


  template <typename L> struct transposed_return<const mpi_distributed_matrix<L> *> 
  { typedef abstract_null_type return_type; };
  template <typename L> struct transposed_return<mpi_distributed_matrix<L> *> 
  { typedef abstract_null_type return_type; };
  
  template <typename L> inline typename transposed_return<const L *>::return_type
  transposed(const mpi_distributed_matrix<L> &l)
  { return transposed(l.M); }

  template <typename L> inline typename transposed_return<L *>::return_type
  transposed(mpi_distributed_matrix<L> &l)
  { return transposed(l.M); }


  template <typename MAT>
  struct linalg_traits<mpi_distributed_matrix<MAT> > {
    typedef mpi_distributed_matrix<MAT> this_type;
    typedef MAT origin_type;
    typedef linalg_false is_reference;
    typedef abstract_matrix linalg_type;
    typedef typename linalg_traits<MAT>::value_type value_type;
    typedef typename linalg_traits<MAT>::reference reference;
    typedef typename linalg_traits<MAT>::storage_type storage_type;
    typedef abstract_null_type sub_row_type;
    typedef abstract_null_type const_sub_row_type;
    typedef abstract_null_type row_iterator;
    typedef abstract_null_type const_row_iterator;
    typedef abstract_null_type sub_col_type;
    typedef abstract_null_type const_sub_col_type;
    typedef abstract_null_type col_iterator;
    typedef abstract_null_type const_col_iterator;
    typedef abstract_null_type sub_orientation;
    typedef abstract_null_type index_sorted;
    static size_type nrows(const this_type &m) { return nrows(m.M); }
    static size_type ncols(const this_type &m) { return ncols(m.M); }
    static void do_clear(this_type &m) { clear(m.M); }
  };

}


#endif // GMM_USES_MPI

namespace std {
  template <typename V>
  void swap(gmm::row_matrix<V> &m1, gmm::row_matrix<V> &m2)
  { m1.swap(m2); }
  template <typename V>
  void swap(gmm::col_matrix<V> &m1, gmm::col_matrix<V> &m2)
  { m1.swap(m2); }
  template <typename T>
  void swap(gmm::dense_matrix<T> &m1, gmm::dense_matrix<T> &m2)
  { m1.swap(m2); }
  template <typename T, int shift> void 
  swap(gmm::csc_matrix<T,shift> &m1, gmm::csc_matrix<T,shift> &m2)
  { m1.swap(m2); }
  template <typename T, int shift> void 
  swap(gmm::csr_matrix<T,shift> &m1, gmm::csr_matrix<T,shift> &m2)
  { m1.swap(m2); }
}




#endif /* GMM_MATRIX_H__ */
