[Coin-ipopt] MA27 error message

[damien at khubla.com]

No, that's not a naive question.  What MA27 is telling you is that it
needs more workspace on the factorisation pass.  It's just a warning and
the factorisation will be re-called automatically by IPOPT with those new
values, hence you see your optimisation run go to completion.  You don't
need to do anything.

Damien


> Hello all,
>
> Forgive me for asking what is possibly a very naïve question, but what
> does this mean? (I get it a lot)
>
>
>   MA27BD returned iflag=-4 and requires more memory.
>    Increase liw from 1607065 to 16070650 and la from   1663110 to
> 16980600 and factorize again.
>
>
> Ipopt 3.1.0 does eventually converge to the optimal solution, but I'm
> worried if this error is indicative of something nasty in my
> formulation? (some badness in the linear system, perhaps?) Or is it
> just a benign warning about needing to adjust the initial memory
> allocation for MA27?
>
> My problem is fairly big:
>
>   32823 variables:
>           9488 nonlinear variables
>           23335 linear variables
>   32837 constraints; 93126 linear nonzeros
>           4850 nonlinear constraints
>           27987 linear constraints
>   1 linear objective; 1 nonzero.
>
> I tried to google 'ma27 and iflag' but this is about the most useful
> link I could find.
> http://tinyurl.com/oyujz
>
> I'd appreciate any comments.
>
> Thanks!
>
> Zhiwen
>
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