[Ipopt] Memory limitations in Matlab-interface IPOPT when using MA27

[Jonathan Hogg]

At a guess its because MA57 will be using scaling by default and MA27 
will not.

For most problems scaling makes little real difference (except that MA57 
runs more slowly), but for others it
significantly reduces (or eliminates completely) need for pivoting and 
the related growth in memory requirements.

You can probably test this by disabling scaling in MA57 and seeing if 
you get similar errors.

Jonathan.

On 16/08/12 08:39, Lemoine, Roberto wrote:
> Dear IPOPT developers/users:
>
> I have a question. I am using the Matlab-interfaced version of IPOPT v.3.10.0 (run with Matlab R2011b in a computer with Windows 7), successfully compiled as described in the Interface website:
>
> bandersnatch.dyndns.info/~djr/ipopt_compile_steps.pdf
>
> My optimization problem is relatively small (1000 degrees of freedom or less). However, IPOPT solves the problem successfully only if I use the linear solver MA57 (I have METIS also installed). However, when I use MA27, IPOPT fails to start iterating, and shows the failure message:
>
> EXIT: Not enough memory
>
> This does not happen with MA57 (even MUMPS makes it to start iterating, but fails after some iterations due to problems in the restoration phase). I have played around by increasing the parameters ma27_liw_init_factor, ma27_la_init_factor and ma27_meminc_factor, and the problem remains.
>
> Does anybody have an idea why MA27 could be having this problems, while MA57 not? Is there a difference in the memory management of the solvers? Thanks a lot in advance.
>
> Best regards,
>
>
> Roberto Lemoine-Nava
>
> Lehrstuhl für Systemdynamik und Prozessführung
> Fakultät Bio- und Chemieingenieurwesen
> Technische Universität Dortmund
> Emil-Figge-Str. 70
> 44221 Dortmund
>
> Tel.: +49 (0) 231/755-5171
>
>
>
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