get_lowbo

Gets the lower bound of a variable.

REAL get_lowbo(lprec *lp, int column);

Return Value

get_lowbo returns the lower bound on the specified variable. If no bound was set, it returns 0, the default lower bound.

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

column

The column number of the variable. It must be between 1 and the number of columns in the lp.

Remarks

The get_lowbo function returns the lower bound on the variable identified by column.
Setting a bound on a variable is the way to go instead of adding an extra constraint (row) to the model. Setting a bound doesn't increase the model size that means that the model stays smaller and will be solved faster.
Note that the default lower bound of each variable is 0. So variables will never take negative values if no negative lower bound is set.

Example

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

int main(void)
{
  lprec *lp;
  REAL a;

  /* Create a new LP model */
  lp = make_lp(0, 2);
  if(lp == NULL) {
    fprintf(stderr, "Unable to create new LP model\n");
    return(1);
  }

  a = get_lowbo(lp, 1); /* will return 0 since no lower bound was set */

  delete_lp(lp);
  return(0);
}

lp_solve API reference