[Scip] SCIP interface with AMPL

[Hans Mittelmann]

Hi,
you have not linked SCIP with IPOPT! Set it to TRUE in Makefile, compile Ipopt and link to it.

Hans Mittelmann

On Sep 30, 2013, at 7:55 AM, Cristiano Arbex <crisarbex at gmail.com> wrote:

> Hi again, 
> 
> I've been using the NEOS server to test SCIP and I've been impressed with its speed. I tried solving 36 nonlinear instances and the largest one can be downloaded here:
> 
> https://docs.google.com/file/d/0B4Rt5z2PACNndUZUc184dVBxQVU/edit?usp=sharing
> 
> It takes NEOS SCIP 6 seconds to solve it. I am using the same scip.set parameters file that can be found on NEOS. I installed the SCIP optimization suite following the steps in the link provided in the first message of this thread. 
> 
> I know my PC is slower than the NEOS server but SCIP on my PC has been solving the same instance for 1200s. In the output file I get this message:
> 
> --------------
> Presolving Time: 4.20
> Quadratic constraint handler does not have LAPACK for eigenvalue computation. Will assume that matrices (with size > 2x2) are indefinite.
> 
>  time | node  | left  |LP iter|LP it/n| mem |mdpt |frac |vars |cons |cols |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap
>   6.5s|     1 |     0 |  1111 |     - |  21M|   0 |   6 |4268 |3217 |4268 |3196 |   0 |  15 |   0 | 0.000000e+00 |      --      |    Inf
>   6.7s|     1 |     0 |  1563 |     - |  21M|   0 |   6 |4268 |3217 |4268 |3196 |   0 |  15 |   0 | 0.000000e+00 |      --      |    Inf
>   6.8s|     1 |     0 |  1575 |     - |  21M|   0 |   6 |4268 |3217 |4268 |3207 |  11 |  15 |   0 | 0.000000e+00 |      --      |    Inf
> --------------
> 
> While NEOS output file looks like this:
> 
> --------------
> Presolving Time: 2.54
> 
>  time | node  | left  |LP iter|LP it/n| mem |mdpt |frac |vars |cons |cols |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap   
>   3.8s|     1 |     0 |  1060 |     - |  21M|   0 |   6 |4268 |3217 |4268 |3196 |   0 |  15 |   0 | 0.000000e+00 |      --      |    Inf 
> 
> ******************************************************************************
> This program contains Ipopt, a library for large-scale nonlinear optimization.
>  Ipopt is released as open source code under the Eclipse Public License (EPL).
>          For more information visit http://projects.coin-or.org/Ipopt
> ******************************************************************************
> 
> q 6.2s|     1 |     0 |  1138 |     - |  21M|   0 |   - |4268 |3217 |4268 |3196 |   0 |  15 |   0 | 0.000000e+00 | 0.000000e+00 |   0.00%
>   6.2s|     1 |     0 |  1138 |     - |  21M|   0 |   - |4268 |3217 |4268 |3196 |   0 |  15 |   0 | 0.000000e+00 | 0.000000e+00 |   0.00%
> --------------
> 
> Do you know why I cannot reproduce such results? Might I be missing something, like the IPOPT nonlinear solver?
> 
> Thank you very much,
> Cristiano
> 
> 
> 
> 
> On Sat, Sep 28, 2013 at 4:30 PM, Cristiano Arbex <crisarbex at gmail.com> wrote:
> Thank you very much, Stefan, that was very helpful.
> 
> 
> On Sat, Sep 28, 2013 at 2:06 PM, Stefan Vigerske <stefan at math.hu-berlin.de> wrote:
> Hi,
> 
> what is not supported so far is to set SCIP options via the AMPL script language.
> However, AMPL/SCIP reads by default SCIP options from the file scip.set, if present.
> 
> Alternatively, one can specify a SCIP settings file as argument to the AMPL/SCIP binary. However, that would require to write out the AMPL model as .nl file first and to run the binary explicitly, e.g.,
>   ./bin/scipampl foo.nl myoptions.set
> 
> Btw, adding "-i" to the command line arguments gives you the SCIP interactive shell.
> 
> Hope that helps,
> Stefan
> 
> 
> 
> On 09/28/2013 01:55 PM, Cristiano Arbex wrote:
> I am trying to use SCIP with its interface to AMPL, which I installed on
> Linux via this following tutorial:
> 
> http://zverovich.net/2012/08/07/using-scip-with-ampl.html
> 
> 
> In the tutorial it is said that no SCIP options are currently supported. Do
> you know if there is a way to use options with AMPL or if there is an
> alternate way to do this, for example, by presenting an options file?
> 
> Thank you very much,
> Cristiano
> 
> 
> 
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> 
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