# OptSlack

## OptSlack(opt)

Returns the slack, or surplus, values for the constraints at the optimal solution. «opt» is a problem specified by DefineOptimization.

As an example, consider the following example constraint:

5 x1 + 3 x2 - x3 <= 14

Suppose the optimal solution is found at (1, 2, 3). Then the left-hand side of this constraint at the optimum is 8. The slack, therefore, is 14 - 8 = 6. In other words, the right-hand side coefficient could be decreased by 6 units before the optimal solution would be impacted.

A slack of zero indicates that the constraint is one that is actively constraining the optimal solution.

## History

This function was introduced in Analytica 4.3. Prior to Analytica 4.3, it was named LpSlack.