ILOG CPLEX 11.0 User's Manual

This routine checks for a valid ILOG CPLEX license and then returns a C pointer to theILOG CPLEX environment that is creates. Your application then passes this C pointer toother ILOG CPLEX routines (except CPXmsg). As a developer, you decide for yourselfwhether the variable containing this pointer should be global or local in your application.Because the operation of checking the license can be relatively time consuming, it isstrongly recommended that you call the CPXopenCPLEX routine only once, or asinfrequently as possible, in a program that solves a sequence of problems.A multithreaded application needs multiple ILOG CPLEX environments. Consequently,ILOG CPLEX allows more than one environment to exist at a time.Note: An attempt to use a problem object in any environment other than the environment(or a child of that environment) where the problem object was created will raise an error.Instantiate the Problem ObjectOnce you have initialized a ILOG CPLEX environment, your next step is to instantiate (thatis, create and initialize) a problem object by calling CPXcreateprob. This routine returns aC pointer to the problem object. Your application then passes this pointer to other routines ofthe Callable Library.Most applications will use only one problem object, though ILOG CPLEX allows you tocreate multiple problem objects within a given ILOG CPLEX environment.Put Data in the Problem ObjectWhen you instantiate a problem object, it is originally empty. In other words, it has noconstraints, no variables, and no coefficient matrix. ILOG CPLEX offers you severalalternative ways to put data into an empty problem object (that is, to populate your problemobject).◆You can make a sequence of calls, in any convenient order, to these routines:●●●●●●●●●CPXaddcolsCPXaddqconstrCPXaddrowsCPXchgcoeflistCPXcopyctypeCPXcopyqsepCPXcopyquadCPXnewcolsCPXnewrows112 ILOG CPLEX 11.0 — USER’ S MANUAL