Returns the index vector which causes the primal simplex or dual simplex algorithm to determine that a problem is primal or dual unbounded respectively.

When solving using the dual simplex method, if the problem is primal infeasible then getunbvec returns the pivot row where dual unboundedness was detected. Also note that when solving using the dual simplex method, if the problem is primal unbounded then getunbvec returns -1 since the problem is dual infeasible and not dual unbounded.

problem.getinfeas, problem.lpoptimize.