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This is an advanced routine. Advanced routines typically demand a profound understanding of the algorithms used by ILOG CPLEX. Thus they incur a higher risk of incorrect behavior in your application, behavior that can be difficult to debug. Therefore, ILOG encourages you to consider carefully whether you can accomplish the same task by means of other Callable Library routines instead.
The routine CPXpivotin forcibly pivots slacks that appear
on a list of inequality rows into the basis. If equality rows appear among
those specified on the list, they are ignored.
Motivation
In the implementation of cutting-plane algorithms for integer programming, it is occasionally desirable to delete some of the added constraints (that is, cutting planes) when they no longer appear to be useful. If the slack on some such constraint (that is, row) is not in the resident basis, the deletion of that row may destroy the quality of the basis. Pivoting the slack in before the deletion avoids that difficulty.
Dual Steepest-Edge Norms
If one of the dual steepest-edge algorithms is in use when this routine is called, the corresponding norms are automatically updated as part of the pivot. (Primal steepest-edge norms are not automatically updated in this way because, in general, the deletion of rows invalidates those norms.)
| env | The pointer to the ILOG CPLEX environment, as returned by |
| lp | A pointer to a CPLEX LP problem object, as returned by |
| rlist | An array of length |
| rlen | An integer that indicates the number of entries in the array |