[Ipopt] solving cops-3 problems with ipopt

[Andreas Waechter]

Hi Dieter,

I have not used the COPS scripts, so I don't know how to use cops_solve.

However, what I see is that you let AMPL write a file called ipopt.opt, 
and it will contain the line

"option ipopt_options 'outlev 1 maxit 5000 max_cpu_time 1800';

But ipopt.opt is the Ipopt options file, which is read by the Ipopt code 
(unless you change its name using the Ipopt/AMPL option 
"option_file_name"), and only works if you have in each line an Ipopt 
options keyword with the assigned value.  Note that outlev and maxit are 
options for Ipopt only available from AMPL (for compatibility reasons). 
So, instead your ipopt.opt file could read

print_level 7
max_iter 5000
max_cpu_time 1800

I hope this helps,

Andreas

On Sun, 16 Aug 2009, Dieter Kraft wrote:

> Hi all subscribers, hi Andreas,
>
> I want to solve cops-3 problems with ipopt-3.7.0 using
> $COPS_HOME/bin/cops_solve
> I copied $COPS_HOME/solvers/minos/initial to
> $COPS_HOME/solvers/ipopt/initial and modified it to
>
> #!/usr/bin/perl -w
>
> open OPTIONS, "> ipopt.opt";
> print OPTIONS "option ipopt_options 'outlev 1 maxit 5000 max_cpu_time
> 1800';\n";
> close OPTIONS;
>
> What I get is the following output in
> $COPS_HOME/output/model/camshape.par1.ipopt.A0.R0.out
>
>
> Presolve eliminates 3 constraints.
> Adjusted problem:
> 50 variables, all nonlinear
> 100 constraints; 247 nonzeros
> 	51 nonlinear constraints
> 	49 linear constraints
> 1 linear objective; 50 nonzeros.
>
> Ipopt 3.7.0: outlev 1
> maxit 5000
> max_cpu_time 1800
>
> Exception of type: OPTION_INVALID in file "IpOptionsList.cpp" at line 638:
> Exception message: Read Option: "option". It is not a valid option. Check
> the list of available options.
> ampl_ipopt.cpp: Error in second Initialize!!!!
> <BREAK>
>
> COPS runtime: 0
>
> which is not what I expect nor want
>
> Thanks for any help
> Dieter
>
> -- 
> Dieter Kraft
> Munich University of Applied Sciences
> kraft at hm.edu
> www.lrz-muenchen.de/~dkraft
>
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