Re: [Bug-glpk] Sensitivity Information not presented in sensitivity bounds file
Hello Andrew, the problem below can be solved by the dual simplex glpsol.exe -m test.mod --dual Yet glp_get_dual_stat() returns GLP_INFEAS dual solution is infeasible for the problem when called in glplpx03.c. The dual values for the constraints are c1: 1.00 c2: 1.00 c3: -0.00e+000 Best regards Xypron UdayV wrote: Hello, I am not sure if this is a bug or not, but I am not able to get sensitivity bounds for the following simple example. Uday Venkatadri --- var x1, = 0; var x2, = 0; maximize z: 3*x1+2*x2; subject to c1: 2*x1+x2 = 100; c2: x1+x2 = 80; c3: x1 = 45; solve; end -- View this message in context: http://www.nabble.com/Sensitivity-Information-not-presented-in-sensitivity-bounds-file-tp25968092p25970225.html Sent from the Gnu - GLPK - Bugs mailing list archive at Nabble.com. ___ Bug-glpk mailing list Bug-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/bug-glpk
Re: [Bug-glpk] Sensitivity Information not presented in sensitivity bounds file
I am not sure if this is a bug or not, but I am not able to get sensitivity bounds for the following simple example. Thank you for the bug report. There is a bug in the bound sensitivity routine: it works only for minimization while your instance is maximization. To avoid the bug you can replace the objective: maximize z: 3*x1+2*x2; by the following one: minimize z: - (3*x1+2*x2); ___ Bug-glpk mailing list Bug-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/bug-glpk
Re: [Bug-glpk] Sensitivity Information not presented in sensitivity bounds file
the problem below can be solved by the dual simplex glpsol.exe -m test.mod --dual Yet glp_get_dual_stat() returns GLP_INFEAS dual solution is infeasible for the problem when called in glplpx03.c. The dual values for the constraints are c1: 1.00 c2: 1.00 c3: -0.00e+000 Thank you. It is still unclear to me, because both primal and dual statuses are GLP_FEAS as reported with '-o' option. ___ Bug-glpk mailing list Bug-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/bug-glpk
Re: [Bug-glpk] Sensitivity Information not presented in sensitivity bounds file
Hi Xypron, the problem below can be solved by the dual simplex glpsol.exe -m test.mod --dual Yet glp_get_dual_stat() returns GLP_INFEAS dual solution is infeasible for the problem when called in glplpx03.c. The dual values for the constraints are c1: 1.00 c2: 1.00 c3: -0.00e+000 The bug is in glp_warm_up, which is called (via lpx_warm_up) from glplpx03. It does not account optimization direction, so the dual status is determined correctly only for minimization. ___ Bug-glpk mailing list Bug-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/bug-glpk
Re: [Bug-glpk] Sensitivity Information not presented in sensitivity bounds file
I am not sure if this is a bug or not, but I am not able to get sensitivity bounds for the following simple example. Thank you for the bug report. The bug will be fixed in the next version of the package. To fix the bug right now please replace file src/glpapi12.c with the patched one (see attachment). It is assumed that you have glpk version 4.39. Andrew Makhorin glpapi12.c.gz Description: GNU Zip compressed data ___ Bug-glpk mailing list Bug-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/bug-glpk
