Re: [Help-gsl] memory requirements of the multiroot algorithms

[Brian Gough]

At Wed, 25 Jul 2007 11:07:15 -0700,
Mark Martin wrote:
> I'm hoping that someone will help me understand the memory
> requirements of the multiroot algorithms.  I'm using GSL routines in
> a simulation of a mechanical system that I've written in C++.  I'm
> trying to use the multiroot solvers to determine equilibrium states
> of the system.  But the multiroot solvers have been failing, even
> for the smallest example, complaining that there isn't enough memory
> to accommodate the required blocks.  A rough calculation, included
> at the bottom of this message, suggests that there should be enough
> memory and my shell doesn't seem to be imposing any artificial
> limitations, i.e. all of the associated ulimit parameters are set to
> "unlimited".
> 
> If the GSL solvers aren't appropriate for my problem, then I would
> very much appreciate any alternative suggestions.  I've poked around
> on the web quite a bit and the alternatives that I've seen all seem
> to be based on MINPACK and seem likely to have the same limitations.

The memory usage of the multiroot solvers should only be O(n^2), so
memory usage for a 154 parameter system should be pretty small.  My
suggestion would be to run the program under gdb, so you can see
exactly where it fails.  Maybe the error message is not the whole
story.  If there is still a problem, try posting a small example
prgram which demonstrates the problem.

-- 
Brian Gough

Network Theory Ltd,
Publishing the GSL Manual - http://www.network-theory.co.uk/gsl/manual/