Hello all, I have some trouble understanding how I can pass an initial basis to GLPK. First of all, with my LP-class, roughly 80-90% of the time is spent with constructing an initial feasible solution. Now of course I'd like to improve this time.
Since I am load balancing a number of flows in a graph, all my variables (except one!) are bound by [0, 1]. And all variables of one load balancing group have to add up to 100%. Now, I can *always* give an initial feasible solution by setting all the variables of one LB-group to 1/x. That is, use 50:50 or 33:33:33 as load balancing scheme. Thus I immediately have a working, but far from optimal, solution. Now I could let the LP solver improve upon that solution, and if I'm restricted by a run time of, say, 10 minutes, I get an acceptable solution. You see, it is better for me, to have a somewhat working solution after a short period, than to wait 90% of the time (hours!) to get the first workable solution (which is very, very good already, but the run time ...) Now I read the GLPK manual and I know that I can only set the status of a variable, not the actual value. What I don't know is, what a basic and a non-basic variable is. What's the difference of an active and non-active constraint? As you already guessed, Linear Programming is not my field of expertise. Any pointers are greatly appreciated! Ulrich Spoerlein -- PGP Key ID: F0DB9F44 Encrypted mail welcome! Fingerprint: F1CE D062 0CA9 ADE3 349B 2FE8 980A C6B5 F0DB 9F44 Ok, which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn." didn't you understand?
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