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Re: Random timing results with 'fsolve'


From: bpabbott
Subject: Re: Random timing results with 'fsolve'
Date: Wed, 12 Oct 2011 14:02:47 +0000 (GMT)

On Oct 12, 2011, at 09:55 AM, Søren Hauberg <address@hidden> wrote:

ons, 12 10 2011 kl. 13:49 +0000, skrev bpabbott:
> On Oct 12, 2011, at 09:41 AM, Søren Hauberg <address@hidden> wrote:
>
>
> > Hi All
> >
> > I am currently using 'fsolve' to solve a non-linear set of
> > equations,
> > for which it works great. However, when I try to determine the
> > running
> > time of the algorithm I get rather different results. I tried
> >
> > for idx = 1:10
> > tic, [a1, b1] = fsolve (g, x, struct ("Jacobian", "off")); tid (idx)
> > = toc;
> > endfor
> >
> > i.e. run the solver ten times with the same input and store running
> > times. After this I see
> >
> > octave:313> max (tid_off) / min (tid_off)
> > ans = 4.2706
> >
> > Does anybody know why I see so large differences in the timing
> > results?
> >
> > Søren
> >
>
>
> Is the first iteration much slower than the rest?
>
>
> Perhaps parsing the code is much slower than actually minimizing the
> objective?

This does not appear to be the problem. Here are the timings for the
different iterations:

27.259
75.303
82.480
32.392
19.313
50.570
42.955
37.075
67.188
44.605

I don't really see any systematic behaviour here :-(

Søren
 
It does look strange.

Have you looked at the 2nd (function values) and 3rd (termination status) outputs of fsolved?

Ben 

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