ILOG CPLEX 11.0 User's Manual > Continuous Optimization > Solving Problems with Quadratic Constraints (QCP) > Identifying a Quadratically Constrained Program (QCP) > Second Order Cone Programming (SOCP)

There is one exception to the PSD requirement; that is, there is an additional form of quadratic constraint which is accepted but is not covered by the general formulation in Identifying a Quadratically Constrained Program (QCP). Technically, the quadratically constrained problem class that the barrier optimizer solves is a Second-Order Cone Program (SOCP). ILOG CPLEX, through its preprocessing feature, makes the translation to SOCP for you, transparently, returning the solution in terms of your original formulation. A constraint will be accepted for solution by the barrier optimizer if it can be transformed to the following convex second-order cone constraint:

images/solveQCPa4.gif

That formulation is distinguished primarily by the specific signs of the coefficients c and by the lack of a linear term, where x0 is a nonnegative variable