> I am using GLPK to solve a problem by column generation. > I have a master problem "MP" which is a Mixed Integer Problem.
> -STEP 1: the dual problem of the relaxed MP is solved iteratively and > new columns are added at each iteration (the new columns are generated > by solving a sub problem), > - STEP 2: the "MP" itself is solved (without relaxation). > I observe the LP objective value of the last iteration of STEP 1, > and I noticed that it may change in the following situations: > 1°) Using GLPK 4.27 compiled with GCC 4.3.0 and using GLPK 4.27 > compiled with GCC 4.2.2, > 2°) Using GLPK 4.27 compiled with GCC 4.2.2 and using GLPK 4.29 > compiled with GCC 4.2.2. Could you send an example in mps or cplex format illustrating that? Is the difference in the objective significant? > Remarks: > -The objectives are the same using GLPK 4.27 and 4.29 both compiled > with GCC 4.3.0, > -The column generator used is the same in all situations, > -The configuration of each compilation was: > ./configure --enable-mysql=no --enable-iodbc=no --with-gmp > My questions are: > 1°) Why do we have different objectives for the same problem, > 2°) Is there an option / a way to obtain the same behavior in each > situation? _______________________________________________ Help-glpk mailing list [email protected] http://lists.gnu.org/mailman/listinfo/help-glpk
