> There is a problem in the functions lpx_write_cpxlp and lpx_read_cpx_lp. > The two operations are not inverses of each other. For instance, when > compiling and executing the file cpxlp_bug.c, a linear programming > problem is created, is written to disk as "a.cpxlp", then read and > written again as "b.cpxlp", and the two files are different. > > Also, the program tries to solve the problems with lpx_simplex: the > original has a solution, not the modified one. > > Perhaps the bound x_1 <= 0 in "a.cpxlp" should have been written -inf <= > x_1 <= 0 instead. > > I am using GLPK version 4.8.
Thank you for your bug report. There is a bug in lpx_read_cpxlp, namely, by default the lower bound is set to 0, so when you specify x <= 0, both lower and upper bound are set to 0 that erroneously gives x = 0. I will fix the bug and post the patch to the list. Andrew Makhorin _______________________________________________ Bug-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/bug-glpk
