[Coin-ipopt] MA27 error message

Zhiwen Chong zhiwen.chong at elf.mcgill.ca
Mon Apr 10 15:18:48 EDT 2006

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.

I'd appreciate any comments.



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