On Monday 28 July 2008, Markus Pilz wrote: > we are working on a tool that utilizes glpk to solve a set of maximum > and minimum cost flows. So far, our approach looks promising. (This > implies a big thank-you to glpk team.) > > Currently, we have some difficulties with larger decision variables. For > example, if the variables of a maximisation problem (max flow) are > limited by values above 1e9, the solution tends to be inexact. > > We still can use the solution as a basis for further processing but > maybe we lack some lp (or glpk) basics to obtain exact values in a wider > range.
Wouldn't it be plausible to run GLPK over precise arithmetics? You can do this by calling lpx_exact instead of lpx_simplex. Network flow problems tend to be seriously overconstrained and thus highly degenerate, calling for numerical instability. An exact solver would solve this issue, for the prize of being somewhat slower. I mean, *really* slower. Best regards, Gabor ---- http://qosip.tmit.bme.hu/~retvari _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
