August 14, 2017 by Tim Johannessen
Scaling Excerpts from Bruce McCarl's Newsletter scaling

Sometimes models do odd things like reporting problems as infeasible, stuck or falsely optimal when scaling is the real issue. To avoid this or correct such issues it is often desirable to check scaling and in turn rescale the model or ask the...


July 27, 2017 by Tim Johannessen
Misbehaving Model – Infeasible Excerpts from Bruce McCarl's Newsletter infeasible artificial variables

Infeasibility is always a possible outcome when solving models. Simplex based linear programming solvers handle infeasibility through a two or three step solution approach. First,there may be some presolution calculations which may determine a model...