/* matrix/submatrix_source.c

 * 

 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Gerard Jungman, Brian Gough

 * 

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 3 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

 * General Public License for more details.

 * 

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 */

QUALIFIED_VIEW(_gsl_matrix,view)

FUNCTION (gsl_matrix, submatrix) (QUALIFIED_TYPE(gsl_matrix) * m, 

                                  const size_t i, const size_t j,

                                  const size_t n1, const size_t n2)

{

  QUALIFIED_VIEW(_gsl_matrix,view) view = NULL_MATRIX_VIEW; 

  if (i >= m->size1)

    {

      GSL_ERROR_VAL ("row index is out of range", GSL_EINVAL, view);

    }

  else if (j >= m->size2)

    {

      GSL_ERROR_VAL ("column index is out of range", GSL_EINVAL, view);

    }

  else if (i + n1 > m->size1)

    {

      GSL_ERROR_VAL ("first dimension overflows matrix", GSL_EINVAL, view);

    }

  else if (j + n2 > m->size2)

    {

      GSL_ERROR_VAL ("second dimension overflows matrix", GSL_EINVAL, view);

    }

  {

     TYPE(gsl_matrix) s = NULL_MATRIX;

     s.data = m->data + MULTIPLICITY * (i * m->tda + j);

     s.size1 = n1;

     s.size2 = n2;

     s.tda = m->tda;

     s.block = m->block;

     s.owner = 0;

     view.matrix = s;     

     return view;

  }

}