Hello Andrew First up, you need to join the [help-glpk] in order to engage further:
http://www.gnu.org/software/glpk/#lists In addition, this might not be a bug but rather a user-domain issue? :) Else it might be an Octave issue? And a matter for the Octave crowd. In any case, I cross-posted this back to [help-glpk]. ------------------------------------------------------------ To: [email protected] Subject: [Bug-glpk] [Fwd: Octave glpk() possible bug] Message-ID: <1370238462.1943.0.camel@corvax> From: Andrew Makhorin <[email protected]> Date: Mon, 03 Jun 2013 09:47:42 +0400 ------------------------------------------------------------ -------- Forwarded Message -------- From: Andrew J. Lewis <[email protected]> Reply-to: "Andrew J. Lewis" <[email protected]> To: [email protected] Subject: Octave glpk() possible bug Date: Mon, 3 Jun 2013 06:40:59 +0100 > Hi! > > I have successfully run our program in Matlab, but > when I ported it substituting glpk() for > bintprog() the program only returns an answer for > low numbers of input values, which is > insufficient. > > I can make Octave work for <=5 input values, but > when I try and run the amended program with the > settings which I ran on Matlab, I get the > following output: > > octave-3.2.4.exe:2> OctaveBeeswax > GLPK Simplex Optimizer, v4.42 > 100 rows, 100 columns, 1058 non-zeros > Preprocessing... > 100 rows, 100 columns, 1058 non-zeros > Scaling... > A: min|aij| = 1.000e+000 max|aij| = 1.000e+000 ratio = 1.000e+000 > Problem data seem to be well scaled > Constructing initial basis... > Size of triangular part = 38 > 0: obj = 1.200000000e+001 infeas = 1.800e+001 (62) > 26: obj = 1.200000000e+001 infeas = 1.800e+001 (40) > PROBLEM HAS NO FEASIBLE SOLUTION This means that the problem you submitted has been proved infeasible by GLPK. Note the word "proved". You should be able to export the problem that GLPK was "supplied" (at least I hope you can under Octave) and examine it directly using GLPSOL and any related tools at your disposal. This strategy effectively removes any issues to do with your inputs, data preparation, Octave's behavior, the Octave/GLPK interface and so on. The other issue concerns bad scaling and related numerical issues. If you export the problem (as just indicated), you can check how well or badly scaled it is, apply various scaling routines, and so on. The insights gained here can then be used to tune you GLPK call (although Octave may not necessarily expose the entire suite of APIs offered by GLPK to the Octave calling environment). > glp_simplex: unable to recover undefined or non-optimal solution > status = 213 > countcir = 0 > opt_positions = [](0x0) > octave-3.2.4.exe:3> > > I would be very grateful, please, for your > opinions as to why repeatedly Octave fails to find > solutions when Matlab does? I have tried every > combination, including generating test data in > Excel. Frustrating I know. But there should be an explanation somewhere. > Best regards, > > Andrew J. Lewis MSc, FLS, MRI > Simul Systems Ltd > Chelmsford, Essex, UK > www.simulsystemsltd.co.uk > M:+44 (0)7710 588318 > F:+44 (0)705 361 1341 > A member of Chelmsford Innovation Group - a "Smart Swarm" business self-help group HTH, Robbie --- Robbie Morrison PhD student -- policy-oriented energy system simulation Technical University of Berlin (TU-Berlin), Germany University email (redirected) : [email protected] Webmail (preferred) : [email protected] [from Webmail client] _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
