Re: [Help-glpk] [Fwd: glpsol not converging]

[glpk xypron]

Hello Narendra,

if tmlim is 100000 (10E5) the optimization should have stopped after 28 hours. 
Please, check you did not enter 1000000 (10E6).

On Linux you can use 
ps -df
to check the parameters of your running process.

To better understand your problem, please, provide:
- last output lines of your "endless" run
- operating system you run on (including whether its 32 or 64bit)
- version of GLPK you are using.
- output of glpsol -m tam.mod -d step1.dat --check

The parameter --first typically will slow down the solution. You should only 
specify it, if you are sure about how your variables are sorted and why you 
want to always branch on the first integer variable.

Best regards

Xypron


-------- Original-Nachricht --------
> Datum: Tue, 31 Jul 2012 15:18:27 -0700
> Von: Narendra Devta-Prasanna <address@hidden>

> Betreff: Re: [Help-glpk] [Fwd: glpsol not converging]

> Hi Xypron, other Experts,
> 
> I have tried with a time limit of 100000 and the run has been going on for
> the last 5 days with no end in sight. It has so far completed 16 million
> iterations with no converging in sight. And the obj value has remained the
> same since ~124000 iteration.
> 
> The options I used to run glpsol are:
> glpsol -m tam.mod -d step1.dat -o step1.out -y step1.res --first --cuts
> --tmlim 100000 --mipgap 0.25
> 
> Can you please suggest to me what I can try to limit this and generate
> *some* solution even if it is not completely optimal but *close* enough.
> 
> Thanks and Regards,
> -Narendra
> 
> On Thu, Jul 26, 2012 at 3:19 PM, Xypron <address@hidden> wrote:
> 
> >  Hello Narendra,
> >
> >
> > >> + 34748: mip =     not found yet >=   1.058800000e+04        (1; 0)
> > >> TIME LIMIT EXCEEDED; SEARCH TERMINATED
> >
> > you have to choose a time limit which is high enough to have a MIP
> > solution.
> >
> > Best regards
> >
> > Xypron
> >
> >
> > On 26.07.2012 23:40, Narendra Devta-Prasanna wrote:
> >
> > Hi Xypron,
> >
> > When I try with "--tmlim 100", the printf commands just print null
> strings
> > for the variables in the ILP. The output file does not have any values
> > assigned for the variables as well. In the end of the output file, I see
> > this:
> >
> > Integer feasibility conditions:
> >
> > KKT.PE: max.abs.err = 0.00e+00 on row 0
> >         max.rel.err = 0.00e+00 on row 0
> >         High quality
> >
> > KKT.PB: max.abs.err = 1.60e+01 on row 34
> >         max.rel.err = 9.41e-01 on row 34
> >         SOLUTION IS INFEASIBLE
> >
> > End of output
> >
> > The log file has this information:
> >
> > * 29500: obj =   1.058950243e+04  infeas =  2.460e-13 (2)
> > * 29725: obj =   1.058800000e+04  infeas =  6.601e-13 (2)
> > OPTIMAL SOLUTION FOUND
> > Integer optimization begins...
> > + 29725: mip =     not found yet >=              -inf        (1; 0)
> > | 32500: obj =   1.058800000e+04  infeas =  3.451e-10 (2)
> > | 33000: obj =   1.058800000e+04  infeas =  4.318e-10 (2)
> > | 33500: obj =   1.058800000e+04  infeas =  4.521e-10 (2)
> > | 34000: obj =   1.058800000e+04  infeas =  5.004e-10 (2)
> > | 34500: obj =   1.058800000e+04  infeas =  2.476e-10 (2)
> > | 34748: obj =   1.058800000e+04  infeas =  4.083e-10 (2)
> > + 34748: mip =     not found yet >=   1.058800000e+04        (1; 0)
> > + 34748: mip =     not found yet >=   1.058800000e+04        (1; 0)
> > TIME LIMIT EXCEEDED; SEARCH TERMINATED
> > Time used:   120.8 secs
> > Memory used: 160.7 Mb (168467811 bytes)
> > Writing MIP solution to `./glpk_ex3/ex3_TAM_IP_glpk_step1.out'...
> >
> > Is it possible to print out the "OPTIMAL SOLUTION FOUND" in some way?
> The
> > actual routing problem I am solving is a non-linear problem which I am
> > modeling as a ILP to get a solution which is anyways not optimal for the
> > problem but happens to be much better than a "random" solution.
> >
> > So, for the ILP, even if it is not an optimal solution, it is acceptable
> > for my situation.
> >
> > Really appreciate your suggestions regarding this...
> >
> > Thanks & Regards,
> > -Narendra
> >
> >
> >