I have posted twice to this list with a problem where Octave under Linux
is unusably slow solving ODEs. (Once with an erroneous solution!) John
Eaton has solved this problem for me and I include part of his e-mail
below, for the list's interest.
Thanks to the people who helped me with this.
John W. Eaton wrote:
> I tried your code on a Linux system and got similarly strange results.
> I noticed that the number of time that the function sEPSP was called
> varied from run to run, which seemed very odd. Then I tried it on an
> Alpha system and got a floating point exception (happening inside
> LSODE). In tracking that down, I found that your state vector s has 4
> elements, but you only use 3, and you only compute 3 derivatives.
> When I changed the line
> s = [0, 0, 0, 0];
> to be
> s = [0, 0, 0];
> I got consistent results.
> Obviously, Octave should check to make sure that the user-supplied
> function computes as many derivatives as there are states, so I've
> added some code to do that.
Department of Anatomy & Cell Biology
University of Melbourne
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