[AMPL 2595] cplex troubleshooting

[Guney Petek]

Greetings,

My model works for a number of instances except for a large instance(~
400000 vars and 200000 cons) on which I am getting this error:
---
Presolve eliminates 34074 constraints and 34074 variables.
...

Error at _cmdno 71 executing "solve" command
(file model.run, line 62, offset 1585):
can't open model.sol
---

I suspect that cplex is dying at some point. In order to trace the
problem I'd like to get more information from cplex along its
progress. What options can I use for troubleshooting cplex?

Thank you, \\Guney

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[Robert Fourer-2]

   option cplex_options 'mipdisplay 2 mipinterval 100 ...';

where ... is replaced by the other options that you are using (or is omitted
if none).  You can change 100 to some other value to regulate the amount of
output.

> -----Original Message-----
> From: ampl@... [mailto:ampl@...]
> On Behalf Of Guney Petek [guneyp@...]
> Sent: Sunday, June 14, 2009 2:13 PM
> To: AMPL Modeling Language
> Subject: [AMPL 2595] cplex troubleshooting
>
>
> Greetings,
>
> My model works for a number of instances except for a large instance(~
> 400000 vars and 200000 cons) on which I am getting this error:
> ---
> Presolve eliminates 34074 constraints and 34074 variables.
> ...
>
> Error at _cmdno 71 executing "solve" command
> (file model.run, line 62, offset 1585):
> can't open model.sol
> ---
>
> I suspect that cplex is dying at some point. In order to trace the
> problem I'd like to get more information from cplex along its
> progress. What options can I use for troubleshooting cplex?
>
> Thank you, \\Guney
>
>

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[Guney Petek]

Thank you for your answer. I began to think that the problem may be
originating somewhere before CPLEX gets called. Using option gentimes
1; I get the error before the CPLEX welcome line:

<...>
## 159         0.42        16.79     27581144  ConstrB
## 161         0.71         17.5     38924672  ConstrC
## 163         2.62        20.12    112940576  ConstrD
## 165         9.38         29.5    341507112  ConstrE
## 167        36.13        65.63 18446744070417967104  ConstrF
Error executing "solve" command:
can't open /tmp/at8714.sol

For smaller instances, right after sequence #167 comes the CPLEX
welcome line "ILOG CPLEX 11.210, licensed to...".

I also tried: option gentimes 0; option times 1; But could not get
much info, either.

<...>
#output 1.13 0 5899101824
#Total 167.03
Error executing "solve" command:
can't open /tmp/at9179.sol
#execute 0.02 0 5899101824

How can I get maximum verbosity in AMPL?

Thanks, \\Guney



On Jun 14, 9:43 pm, "Robert Fourer" <4...@...> wrote:

>    option cplex_options 'mipdisplay 2 mipinterval 100 ...';
>
> where ... is replaced by the other options that you are using (or is omitted
> if none).  You can change 100 to some other value to regulate the amount of
> output.
>
> > -----Original Message-----
> > From: ampl@... [mailto:ampl@...]
> > On Behalf Of Guney Petek [gun...@...]
> > Sent: Sunday, June 14, 2009 2:13 PM
> > To: AMPL Modeling Language
> > Subject: [AMPL 2595] cplex troubleshooting
>
> > Greetings,
>
> > My model works for a number of instances except for a large instance(~
> > 400000 vars and 200000 cons) on which I am getting this error:
> > ---
> > Presolve eliminates 34074 constraints and 34074 variables.
> > ...
>
> > Error at _cmdno 71 executing "solve" command
> > (file model.run, line 62, offset 1585):
> > can't open model.sol
> > ---
>
> > I suspect that cplex is dying at some point. In order to trace the
> > problem I'd like to get more information from cplex along its
> > progress. What options can I use for troubleshooting cplex?
>
> > Thank you, \\Guney
>
>

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