> I am experimenting with various solvers and techniques and I have > relied on glpsol to translate my MathProg models to .lp and .mps > files but I am now convinced that the .mps files are not equivalent > to the MathProg (or even the .lp) files.
I did find that that caused the error. Thank you for your report. In your mps file there is column C0000151 (corresponding to variable maxnbs in your model) which is marked as integer, however, it is missing in the BOUNDS section. By default glpk assigns its lower/upper bounds to 0 and +inf, resp. On the other hand the mps format specification (IBM OSL) states that any integer column is considered as binary (i.e. with upper bound 1) until its upper bound is specified explicitly in the BOUNDS section (to make it unbounded the user should specifiy its upper bound as 1e30). To my opinion this is a quirk, because many mip solvers do not like unbounded integer variables. Of course, I will introduce an appropriate option in corresponding api routines and glpsol. To avoid the error you need to specify both lower and upper bounds for every integer variable in the model. Andrew Makhorin _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
