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/* bfx.c (LP basis factorization driver, rational arithmetic) */
/***********************************************************************
* This code is part of GLPK (GNU Linear Programming Kit).
*
* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
* 2009, 2010, 2011, 2013 Andrew Makhorin, Department for Applied
* Informatics, Moscow Aviation Institute, Moscow, Russia. All rights
* reserved. E-mail: <mao@gnu.org>.
*
* GLPK 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.
*
* GLPK 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 GLPK. If not, see <http://www.gnu.org/licenses/>.
***********************************************************************/
#include "bfx.h"
#include "env.h"
#include "lux.h"
struct BFX
{ int valid;
LUX *lux;
};
BFX *bfx_create_binv(void)
{ /* create factorization of the basis matrix */
BFX *bfx;
bfx = xmalloc(sizeof(BFX));
bfx->valid = 0;
bfx->lux = NULL;
return bfx;
}
int bfx_factorize(BFX *binv, int m, int (*col)(void *info, int j,
int ind[], mpq_t val[]), void *info)
{ /* compute factorization of the basis matrix */
int ret;
xassert(m > 0);
if (binv->lux != NULL && binv->lux->n != m)
{ lux_delete(binv->lux);
binv->lux = NULL;
}
if (binv->lux == NULL)
binv->lux = lux_create(m);
ret = lux_decomp(binv->lux, col, info);
binv->valid = (ret == 0);
return ret;
}
void bfx_ftran(BFX *binv, mpq_t x[], int save)
{ /* perform forward transformation (FTRAN) */
xassert(binv->valid);
lux_solve(binv->lux, 0, x);
xassert(save == save);
return;
}
void bfx_btran(BFX *binv, mpq_t x[])
{ /* perform backward transformation (BTRAN) */
xassert(binv->valid);
lux_solve(binv->lux, 1, x);
return;
}
int bfx_update(BFX *binv, int j)
{ /* update factorization of the basis matrix */
xassert(binv->valid);
xassert(1 <= j && j <= binv->lux->n);
return 1;
}
void bfx_delete_binv(BFX *binv)
{ /* delete factorization of the basis matrix */
if (binv->lux != NULL)
lux_delete(binv->lux);
xfree(binv);
return;
}
/* eof */
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