> I think I've come across a bug with the function 'lpx_write_cpxlp' for > writing linear programs in CPLEX LP format. The problem is with upper > bounded variables that do not have lower bound. Such a variable say x is > written by GLPK as x <= upper_bound in the Bounds section of the LP > file. But since variables in LP format are understood to be > non-negative, in fact CPLEX understands 0 <= x <= upper_bound, which is > not the intended meaning. Instead, GLPK should write something like -Inf > <= x <= upper_bound. I attach a program that produces an LP file which, > once fed into CPLEX, allows one to see the error if CPLEX is asked to > write the linear program again (or if it is asked for the lower bound of > the variable).
Thank you for your bug report. The bug will be fixed in a next release of the package. To fix the bug right now please replace line 1134 (file glplpx16.c, routine lpx_write_cpxlp): fprintf(fp, " %s <= %.*g\n", cname, DBL_DIG, ub); by the following line: fprintf(fp, " -inf <= %s <= %.*g\n", cname, DBL_DIG, ub); > By the way, congratulations on your excellent code. :-) Thank you for your interest in glpk. _______________________________________________ Bug-glpk mailing list Bug-glpk@gnu.org http://lists.gnu.org/mailman/listinfo/bug-glpk
