On Fri, 2017-06-16 at 07:59 -0500, Shuo Xu wrote: > Hi, Andrew, > > I think I find a bug that: > > I am using a special case that : > > I have a special matrix A with m-by-n, and write lp with > glp_write_lp. > > And, I read the written-lp file, the matrix A is not the same as the > original matrix A. > > > So, would you like to see that case to help me?
It happens if your instance has double-bounded rows, i.e. rows like l <= ... <= u. Cplex lp format has no feature to specify such rows, so glp_write_lp introduces additional rows and columns which are missing in the original lp. To avoid these troubles and keep the instance unchanged on reading it from a file I recommend you to use glpk lp/mip format provided by the api routines glp_read_prob and glp_write_prob. > > > Shuo > > > > > On Thu, Jun 15, 2017 at 9:55 AM, Shuo Xu <[email protected]> > wrote: > thanks, Andrew, > > > I think I can deal with this problem by re-assigning the > problem-name using glp_set_prob_name. > > > Shuo > > > > > > On Thu, Jun 15, 2017 at 9:49 AM, Andrew Makhorin <[email protected]> > wrote: > > > well, as far I read the LP-file generated by glpk, > it put the name in > > the first line as > > " > > \* Problem: Level_1 *\ > > > > Minimize > > obj: - 8 x_1.............................. > > " > > > > although this is just a comment line, but we (you) > have put the > > LP_Name here. > > > > So, I think this is the way to get a file name > there. > > It is not a good idea, because it would be a > non-standard feature. > > If you need to keep all problem components on reading > the instance, > which was previously written to a file with glpk, I'd > recommend you > using the glpk lp format. > > > > > > > So, it looks that <glp_write_lp> and <glp_read_lp> > are not > > compatible. > > > > :) > > > > > _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
