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Purpose
Change the lower or upper bound for a single variable.
Synopsis
int QSchange_bound (QSprob p, int indx, char lu, double bound)
Arguments
p a handle to an initialized problem.
indx the index of the variable whose bound will be changed.
lu an 'L' to change the lower bound or a 'U' to change an upper bound.
bound the value of the new bound.
Returns
A zero value if the function terminated correctly, and a non-zero value if an error occurred.
Description

This function can be used to change the lower or upper bound of a single variable. A bound on a variable can be removed by specifying -QS_MAXDOUBLE as a lower bound, or QS_MAXDOUBLE as an upper bound. A common use of this function is to fix a variable at its lower or upper bound, or to change a bound in a step of a branch-and-bound algorithm.

When specifying the lower or upper bound, it is important not to give any value larger in magnitude than QS_MAXDOUBLE (1e30). This restriction is due to the internal structures used in the QSopt solvers.

Example
/* Assume p is initialized to the problem in the QSload_prob example. */
/* Change the lower bound on variable y to 0.                         */

int rval;
rval = QSchange_bound (p, 1, 'L', 0.0);
if (rval) {
    fprintf (stderr, 
             "Could not change the bound, error code %d\n",rval);
}
 
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Last Updated: November 2003