ILOG CPLEX 11.0 User's Manual

QMATRIXC158 C158 1C158 C189 0.5C189 C158 0.5C189 C189 1QCMATRIX QC1C157 C157 1C157 C158 0.5C158 C157 0.5C158 C158 1C159 C159 1C160 C160 1QCMATRIX QC2C161 C161 2C162 C162 2C163 C163 1QCMATRIX QC3C164 C164 1C165 C165 1QCMATRIX QC4C166 C166 1C167 C167 1C168 C168 1C169 C169 1C171 C171 1ENDATAChanging Problem TypeBy default, every model in Concert Technology is the most general problem type possible.Consequently, it is not necessary to declare the problem type nor to change the problem type,even if you add quadratic constraints to the model or remove them from it. In contrast, boththe Callable Library and the Interactive Optimizer need for you to indicate a change inproblem type explicitly if you remove the quadratic constraints that make your model a QCP.In both the Callable Library and Interactive Optimizer, if you want to remove the quadraticconstraints in order to solve the problem as an LP or a QP, then you must first change theproblem type, just as you would, for example, if you removed the quadratic coefficients froma quadratic objective function.From the Callable Library, use the routine CPXchgprobtype to change the problem type toCPXPROB_LP if you remove the quadratic constraints from your model in order to solve it asan LP. Contrariwise, if you want to add quadratic constraints to an LP or a QP model andthen solve it as a QCP, use the routine CPXchgprobtype to change the problem type toCPXPROB_QCP.When using the Interactive Optimizer, you apply the command change problem with oneof the following options:ILOG CPLEX 11.0 — USER’ S MANUAL 249