Re: [Help-glpk] Objective value issue

[Heinrich Schuchardt]

Hello Mattia,

please, provide an example model.

Best regards

Heinrich Schuchardt

http://www.xypron.de

Am 11.07.14 um 17:41 schrieb Mattia Buccarella

> Thanks for your answer.
> 
> The link you suggested is the one I already saw and discussed in my first
> 
> email.
> 
> My question is about the meaning of "constant", since all the terms in my
> 
> objective function are functions of variables (i.e.: none of them is
> 
> actually constant). Also, I would like to know if there is any way not to
> 
> let this shift happen.
> 
> Thank you again for your time.
> 
> 
> 
> --
> 
> Mattia Buccarella
> 
> 
> 
> 
> 
> On Fri, Jul 11, 2014 at 5:35 PM, Heinrich Schuchardt <address@hidden>
> 
> wrote:
> 
> 
> 
> > Hello Mattia,
> 
> >
> 
> > please, read
> 
> >
> 
> > http://en.wikibooks.org/wiki/GLPK/Troubleshooting#Objective_shift_term_ignored_when_exported
> 
> >
> 
> > Best regards
> 
> >
> 
> > Heinrich Schuchardt
> 
> >
> 
> > http://www.xypron.de
> 
> >
> 
> > Am 11.07.14 um 17:20 schrieb Mattia Buccarella
> 
> >
> 
> > > Hello everyone,
> 
> > >
> 
> > >
> 
> > >
> 
> > > my name is Mattia and I am using glpsol in the development of my master
> 
> > >
> 
> > > thesis in computer science.
> 
> > >
> 
> > >
> 
> > >
> 
> > > I am writing to you all for something I could not find anywhere so far.
> 
> > >
> 
> > > When I use glpsol to solve my model (written in MathProg, with separate
> 
> > >
> 
> > > data input file), all the variables are configured properly as I expect
> 
> > (I
> 
> > >
> 
> > > am referring to a "dummy" input I use to verify the correctness of my
> 
> > >
> 
> > > model). Nevertheless, the value of the objective function is shifted and
> 
> > I
> 
> > >
> 
> > > get the following message:
> 
> > >
> 
> > >
> 
> > >
> 
> > > Model has been successfully generated
> 
> > >
> 
> > > *glp_mpl_build_prob: row obje; constant term 84384 ignored*
> 
> > >
> 
> > > GLPK Integer Optimizer, v4.52
> 
> > >
> 
> > > ...etc...
> 
> > >
> 
> > >
> 
> > >
> 
> > > Searching the web, I found somebody had a similar issue but it was not
> 
> > >
> 
> > > related to the objective function and also involved CPLEX (context very
> 
> > >
> 
> > > different from mine). Does anybody of you know what is happening? When I
> 
> > >
> 
> > > try to solve the model (same model, same input) with COIN-OR Cbc, through
> 
> > >
> 
> > > AMPL, it gives me the non-shifted value. Also, it does not tell me
> 
> > anything
> 
> > >
> 
> > > about constant terms in the function. Also, I checked again and again my
> 
> > >
> 
> > > objective function: all the terms are functions of some variable, so
> 
> > >
> 
> > > nothing is really constant in the calculation.
> 
> > >
> 
> > >
> 
> > >
> 
> > > Thanks in advance for your help.
> 
> > >
> 
> > > Goodbye.
> 
> > >
> 
> > >
> 
> > >
> 
> > > --
> 
> > >
> 
> > > Mattia Buccarella
> 
> > >
> 
> > > _______________________________________________
> 
> > >
> 
> > > Help-glpk mailing list
> 
> > >
> 
> > > address@hidden
> 
> > >
> 
> > > https://lists.gnu.org/mailman/listinfo/help-glpk
> 
> >