Hi, I am getting back to this subject because I am facing a small problem using GLPK both on Windows and Linux. As I said in my previous e-mail, I managed to compile the library to use GLPK in java for Linux, and it works fine. However, I get a difference when running an instance under Windows on the one hand and on Linux on the other hand: it is the same optimal solution (same primal values for variables), but the basis is different, as well as the dual values of constraints and variables. It is a problem as I need to use these dual values in a Branch-and-Price algorithm to get new columns. During my investigation, I saw a difference that might be linked to this behaviour: when printing the solution into a file (using glp_print_sol), the Karush-Kuhn-Tucker optimality conditions (at the end) don't provide exactly the same display. On the one hand (Linux), there are 2 digits for the powers of 10 (ex: 0.00e+00), and on the other hand (Windows), there are 3 (ex: 0.00e+000). Could the problem I am facing be linked to a rounding problem? If so, how can I make the result identical for Windows and Linux? If you need the model for which this problem occurs, feel free to ask.
Sylvain 2009/6/1 Sylvain Fournier <[email protected]> > I just tested it (only the target "all" of the Makefile), and it seems to > work well. Many thanks Xypron! > I have to point out that I had to make small changes in the Makefile to > make it work: > In the first call to libtool (gcc ... src/java/glpk_wrap.c), I had to add > "-I$(PREFIX)/include" because I had some errors. > In the second call of libtool, I got the following error : "/usr/bin/ld: > cannot find -lgmp" > So, I removed -lgmp, and it worked! Is this library really necessary? What > is the use of the other (ltdl)? > > Sylvain > > > Date: Sun, 31 May 2009 08:38:39 -0700 (PDT) >> From: xypron <[email protected]> >> Subject: [Help-glpk] Compiling GLPK for Java under Linux >> To: [email protected] >> Message-ID: <[email protected]> >> Content-Type: text/plain; charset=us-ascii >> >> >> Hello Sylvain >> >> Sylvain Fournier wrote: >> > >> > I then saw that there is a glpk_4_38_java library available ( >> > http://winglpk.sourceforge.net/), >> > ... has the glpk_4_38_java.dll also been compiled under >> > Linux as a .so? >> > >> I have created a Makefile and added a source code package >> >> https://sourceforge.net/project/downloading.php?group_id=244007&filename=glpk-java-4.38.tar.gz&a=38892371 >> glpk-java-4.38.tar.gz<https://sourceforge.net/project/downloading.php?group_id=244007&filename=glpk-java-4.38.tar.gz&a=38892371%0Aglpk-java-4.38.tar.gz> >> to the download page of http://winglpk.sourceforge.net/ GLPK for Windows >> . >> >> Best regards >> >> Xypron > > >
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