sc_simplex_feasibility.c

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/*
 
  $Id: sc_simplex_feasibility.c 1669 2019-06-26 17:24:57Z coelho $
 
  Copyright 1989-2016 MINES ParisTech
 
  This file is part of Linear/C3 Library.
 
  Linear/C3 Library is clear software: you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the clear Software Foundation, either version 3 of the License, or
  any later version.
 
  Linear/C3 Library 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 Linear/C3 Library.  If not, see <http://www.gnu.org/licenses/>.
 
*/
 
/**
 * @file
 * This file provides a function to test whether a constraint system is
 * feasible, using simplex method.
 */
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <stdlib.h>
 
#include "boolean.h"
#include "linear_assert.h"
#include "vecteur.h"
#include "contrainte.h"
#include "sc.h"
 
#define WNOGMP (fprintf(stderr, "[" __FILE__ "] linear was compiled without GMP support\n"))
 
static bool usegmp()
{
        char* env = getenv("LINEAR_USE_GMP");
        return env && atoi(env) != 0;
}
 
/**
 * Main Function
 */
/**@{*/
 
/**
 * Determine whether a system @a sys of equations and inequations is feasible.
 * Parameter @a ofl_ctrl indicates whether an overflow control is performed
 * (possible values: @c NO_OFL_CTRL, @c FWD_OFL_CTRL).
 */
bool sc_simplex_feasibility_ofl_ctrl(Psysteme sys, int ofl_ctrl)
{
        if (usegmp()) {
#ifdef HAVE_GMP_H
                return sc_simplex_feasibility_ofl_ctrl_mulprec(sys, ofl_ctrl);
#else
                WNOGMP;
                return sc_simplex_feasibility_ofl_ctrl_fixprec(sys, ofl_ctrl);
#endif
        }
        else {
                return sc_simplex_feasibility_ofl_ctrl_fixprec(sys, ofl_ctrl);
        }
}
 
/**@}*/