is_do_presolve

Returns a flag if a presolve must be done before solving.

short is_do_presolve(lprec *lp);

Return Value

is_do_presolve returns TRUE or FALSE. Do presolve or not.

Parameters

Pointer to previously created lp model. See return value of make_lp, copy_lp, read_lp, read_lp_file, read_LP, read_mps, read_MPS

Remarks

The is_do_presolve function returns a flag if a presolve must be done before solving. Presolve looks at the model and tries to simplify it so that solving times are shorter. For example a constraint on only one variable is converted to a bound on this variable (and the constraint is deleted). Note that the model dimensions can change because of this, so be careful with this. Both rows and columns can be deleted by the presolve.
The default is not (FALSE) doing a presolve.

Example

#include <stdio.h>
#include <stdlib.h>
#include "lpkit.h"

int main(void)
{
  lprec *lp;
  short presolve;

  /* Create a new LP model */
  lp = make_lp(0, 0);
  if(lp == NULL) {
    fprintf(stderr, "Unable to create new LP model\n");
    return(1);
  }

  presolve = is_do_presolve(lp); /* Will return FALSE */

  delete_lp(lp);
  return(0);
}

lp_solve API reference