> When I run this I get the output below. The first call to the (primal) > simplex found an optimal solution at iteration 80153. The second call, > after moving some lower bounds from 0 to some positive integer, found a > solution 7000 iterations later.
Ok. Now the second call to lpx_simplex provides reoptimization. > I guess that I expected the > infeasibility to be reported as the dual infeasibility, but my current > guess is that the reported infeasibility is always primal infeasibility > even when running the dual simplex algorithm. Is that correct? That is correct. However, the infeasibility reported by the simplex routines is an internal quantity intended for visual estimation only unlike the objective value which always corresponds to the original problem instance. For example, in the primal simplex it is a relative quantity which is set to 1 at the beginning of the search, and in the dual simplex it is a sum of infeasibilities for an internally scaled (and possibly presolved) problem instance. You can recognize which version of the simplex is used by the first character displayed on the screen: '|' means the dual simplex while ' ' and '*' means the primal simplex (phase I and II respectively). _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
