The difference is the preprocessing. If the problem has, for example, x variables (say 192), it is possible that after preprocessing (activated with presolve) the problem has less than x variables (say 186). glp_ios_heur_sol would need 186 but you give him 192 variables. That's why you had those problems with initial solutions.
- G. S. - Il giorno 06/ago/2013, alle ore 13:13, Le Dinh Danh <[email protected]> ha scritto: > Oh great! It works now. Thank you so much G.S. I try your way and it > is correct now. > However, I really don't know why. I thought that the default presolve > in GLPK using simplex method and it should work the same as we call > simplex solver (with parm.presolve = OFF). > It takes me a lot of time. Thank you once again and good work! > > On Tue, Aug 6, 2013 at 12:42 PM, Giorgio Sartor <[email protected]> wrote: >> Ok. I really think that the problem is the presolve because I had the same >> problem months ago. >> At least just try adding glp_simplex before glp_intopt and disable presolve. >> Presolve is not default in GLPK. >> >> >> - G. S. - >> >> Il giorno 06/ago/2013, alle ore 12:31, Le Dinh Danh <[email protected]> ha >> scritto: >> >>> Oh I forgot to tell you that I suppose to use the default presolve in >>> GLPK and do not explicit use any other for it. I know that if I don't >>> use the presolve default I have to use some presolve like simplex or >>> so. So in my case parm.presolve = ON is neccesary. >>> For my heuristic solutions I am sure that they are correct, because I >>> can verify it manually myself. >>> >>> On Tue, Aug 6, 2013 at 12:23 PM, Giorgio Sartor <[email protected]> wrote: >>>> Well, I don't know what you mean exactly but setting parm.presolve = ON is >>>> never NECESSARY! (It is necessary only if you don't want to use glp_simplex >>>> before glp_intopt). If you don't use it, my suggestion is to use >>>> glp_simplex >>>> before glp_intopt and disable parm.presolve. In this case, if the integer >>>> solution found is incorrect means that the solution you pass is incorrect. >>>> >>>> >>>> 2013/8/6 Le Dinh Danh <[email protected]> >>>>> >>>>> Hi G.S, >>>>> It is neccesary to set parm.presolve=ON before solving MIP. In fact, I've >>>>> tried with parm.presolve=OFF but the results are always 0. Anyway, thank >>>>> you. >>>>> >>>>> >>>>> On Mon, Aug 5, 2013 at 5:34 PM, Giorgio Sartor <[email protected]> wrote: >>>>>> >>>>>> Ok. Just try parm.presolve=OFF and let me know if then works. >>>>>> >>>>>> >>>>>> - G. S. - >>>>>> >>>>>> Il giorno 05/ago/2013, alle ore 16:51, Le Dinh Danh <[email protected]> ha >>>>>> scritto: >>>>>> >>>>>> Hi Giorgio Sartor, >>>>>> >>>>>> On Mon, Aug 5, 2013 at 4:14 PM, Giorgio Sartor <[email protected]> >>>>>> wrote: >>>>>>> >>>>>>> Is glp_iocp.presolve activated? >>>>>> >>>>>> Yes, I have already set parm.presolve = ON. >>>>>>> >>>>>>> A common cause of incorrect solutions is that your solution is correct >>>>>>> for the original problem but not correct for the current problem (which >>>>>>> could have been modified by GLPK during the solving process). >>>>>>> Stupid question: does your solution start from position 1 of the array? >>>>>> >>>>>> Yes, of course. >>>>>>> >>>>>>> >>>>>>> - G. S. - >>>>>>> >>>>>>> Il giorno 05/ago/2013, alle ore 14:58, Le Dinh Danh <[email protected]> >>>>>>> ha scritto: >>>>>>> >>>>>>> With "the result is still incorrect" I mean after calling the callback >>>>>>> function, the solver find the solution but it is not correct one. I >>>>>>> don't >>>>>>> know why. If I don't call the cacllback, the solve provide a good >>>>>>> solution. >>>>>>> I can check it manually. >>>>>>> >>>>>>> >>>>>>> On Mon, Aug 5, 2013 at 1:19 PM, Giorgio Sartor <[email protected]> >>>>>>> wrote: >>>>>>>> >>>>>>>> What do you mean with "the result is still incorrect"? >>>>>>>> >>>>>>>> >>>>>>>> - G. S. - >>>>>>>> >>>>>>>> Il giorno 05/ago/2013, alle ore 12:57, Le Dinh Danh <[email protected]> >>>>>>>> ha scritto: >>>>>>>> >>>>>>>>> the result is still incorrect. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Le Dinh Danh >>>>>>> LIRMM, 161 rue Ada, 34095 Montpellier Cedex 5 >>>>>>> Email: [email protected]; [email protected] >>>>>>> Tel: (+84) 912.449.666; (+33) 6.52.98.59.66 >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Le Dinh Danh >>>>>> LIRMM, 161 rue Ada, 34095 Montpellier Cedex 5 >>>>>> Email: [email protected]; [email protected] >>>>>> Tel: (+84) 912.449.666; (+33) 6.52.98.59.66 >>>>> >>>>> >>>>> >>>>> -- >>>>> Le Dinh Danh >>>>> LIRMM, 161 rue Ada, 34095 Montpellier Cedex 5 >>>>> Email: [email protected]; [email protected] >>>>> Tel: (+84) 912.449.666; (+33) 6.52.98.59.66 >>> >>> >>> >>> -- >>> Le Dinh Danh >>> LIRMM, 161 rue Ada, 34095 Montpellier Cedex 5 >>> Email: [email protected]; [email protected] >>> Tel: (+84) 912.449.666; (+33) 6.52.98.59.66 > > > > -- > Le Dinh Danh > LIRMM, 161 rue Ada, 34095 Montpellier Cedex 5 > Email: [email protected]; [email protected] > Tel: (+84) 912.449.666; (+33) 6.52.98.59.66 _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
