Thanks. I was out of town at the time and missed it in the backlog. I noticed in profiling the examples that trick.mod seems to get into trouble. I killed it after an hour, but I'm going to look at what's happening. Interestingly it completes in 100 seconds using --pcost.
Algorithm matters a lot in problems like these. I was doing large (10**6 points) Delauney triangulations using Renka's TRIPACK code from TOMS and had a problem go into an infinite loop because of floating point issues. I discovered the problem after having jobs run for several days w/o completing. I had run the code many times prior to that case. It took quite a bit of work to develop a small example. Fortune's sweep algorithm doesn't encounter a problem. FWIW The Delauney triangulation in n dimensions is the projection of the convex hull in n+1 dimensions. So there are very important connections between linear programming and computational geometry. In light of the trick.mod behavior, parallelizing multiple heuristics for the MIP problem might be a big practical gain. Setup the problem, solve the LP case and then spawn multiple MIP threads which all terminate when one succeeds. Pingqi Pan's results suggest that a similar strategy might be useful for simplex as well. Certainly not what I had in mind when I raised the subject, but if you're solving lots of instances, mean time to solution is what matters. Have Fun! Reg --- On Sun, 12/16/12, Harley Mackenzie <[email protected]> wrote: > From: Harley Mackenzie <[email protected]> > Subject: Re: [Help-glpk] Multithreading/parallelization > To: "Reginald Beardsley" <[email protected]> > Cc: "GLPK-HELP" <[email protected]> > Date: Sunday, December 16, 2012, 6:09 PM > This was posted: > > Meindl and Templ (2012) solver survey by Robbie > Morrison Nov 06, 2012; > 09:36pm > > Meindl, Bernhard and Matthias Templ. 2012. > Analysis of commercial and free and > open > source solvers for linear optimization > problems. Report. 23 > February 2012. > > download: > http://neon.vb.cbs.nl/casc/..%5Ccasc%5CESSNet2%5Cdeliverable_solverstudy.pdf > > Recommended reading, especially the number of the MIP > problems solved by > GLPK compared to the commercial codes. > > Harley > > On Sun, Dec 16, 2012, at 9:56, Reginald Beardsley wrote: > > What recent paper? > > -- > ----- > Dr. Harley Mackenzie > HARD software > > [email protected] > www.hardsoftware.com > + 61 3 5222 3435 > _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
