CPXpresolve

int CPXPUBLIC CPXpresolve(CPXCENVptr env, CPXLPptr lp, int method)

Definition file: cplex.h

Include files: cplex.h

Note

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 CPXpresolve performs LP or MIP presolve depending whether a problem object is an LP or a MIP. If the problem is already presolved, the existing presolved problem is freed, and a new presolved problem is created.

Example

 status = CPXpresolve (env, lp, CPX_ALG_DUAL);

Parameters:

env	A pointer to the CPLEX environment, as returned by `CPXopenCPLEX`.
lp	A pointer to a CPLEX LP problem object, as returned by `CPXcreateprob`.
method	An integer specifying the optimization algorithm to be used to solve the problem after the presolve is completed. Some presolve reductions are specific to an optimization algorithm, so specifying the algorithm makes sure that the problem is presolved for that algorithm, and that presolve does not have to be repeated when that optimization routine is called. Possible values are `CPX_ALG_NONE`, `CPX_ALG_PRIMAL`, `CPX_ALG_DUAL`, and `CPX_ALG_BARRIER` for LP; `CPX_ALG_NONE` should be used for MIP.

Returns:

The routine returns zero on success and nonzero if an error occurs.