set_rh_range

Set the range on a constraint.

unsigned char set_rh_range(lprec *lp, int row, REAL deltavalue);

Return Value

set_rh_range returns TRUE (1) if the operation was successful. A return value of FALSE (0) indicates an error.

Parameters

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

row

The row number of the constraint on which the range must be set. It must be between 1 and the number of rows in the lp.

deltavalue

The range on the constraint.

Remarks

The set_rh_range function sets a range on the constraint (row) identified by row.
Setting a range on a row is the way to go instead of adding an extra constraint (row) to the model. Setting a range doesn't increase the model size that means that the model stays smaller and will be solved faster.
If the row has a less than constraint then the range means setting a minimum on the constraint that is equal to the RHS value minus the range. If the row has a greater than constraint then the range means setting a maximum on the constraint that is equal to the RHS value plus the range.
Note that the range value is the difference value and not the absolute value.

Example

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

int main(void)
{
  lprec *lp;

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

  set_rh_range(lp, 1, 1.0);

  delete_lp(lp);
  return(0);
}

lp_solve API reference