# is_negative Returns if the variable is negative. unsigned char is_negative(lprec *lp, int column); Return Value is_negative returns TRUE (1) if the variable is defined as negative, FALSE (0) otherwise. Parameters lp 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 column The column number of the variable that must be checked. It must be between 1 and the number of columns in the lp. Remarks The is_negative function returns if a variable is negative or not. Negative means a lower and upper bound that are both negative. Default a variable is not free because default it has a lower bound of 0 (and an upper bound of +infinity). Example
    #include <stdio.h>
    #include <stdlib.h>
    #include "lp_lib.h"

    int main(void)
    {
      lprec *lp;
      int negative;

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

      negative = is_negative(lp, 1); /* will return 0 since the variable is not set as negative at this point */

      delete_lp(lp);
      return(0);
    }
lp_solve API reference See Also make_lp, copy_lp, read_lp, read_LP, read_mps, read_freemps, read_MPS, read_freeMPS, read_XLI, get_upbo, set_upbo, set_lowbo, get_lowbo, set_bounds, is_unbounded, set_unbounded