[Coin-ipopt] MA27 error message

[Carl Damon Laird]

Damien is correct, you do not need to do anything. If Ipopt has not 
reserved enough memory for ma27, ma27 exits and Ipopt allocates more 
memory and calls ma27 again.

If you want things to go a little faster, you can set the options 
ma27_liw_init_factor and ma27_la_init_factor (also look at 
ma27_meminc_factor) to reserve enough memory ahead of time. This will keep 
Ipopt from calling ma27 multiple times for the same factorization.

Cheers,

Carl.


On Mon, 10 Apr 2006 damien at khubla.com wrote:

> 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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>
>
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