Hi,
months ago I had the same problems. It was enlightening for me to have a
look into the sources. There are two functions, the solver and
solver_many. The latter does not do iters_fixed_t calculations but tries
n_tries points in the neighborhood, choosing the best step (and lowering
the temperature immediately). So if you choose the "normal" solver only
the iters_fixed_t variable is considered, while for solver_many only the
n_tries variable is taken into account.
Hope that helps
Benjamin
Sak wrote:
I'm trying to use the simulated annealing module of GSL. I understand the
algorithm pretty well and the settings parameters passed to the main SA
function
in the gsl_siman_params_t data structure.
I believe iters_fixed_t is the length of the random walk at each
temperature. Is
this correct?
And, I don't understand the meaning of n_tries from the GSL documentation:
"The number of points to try for each step." From what I understand of SA,
if the e_i+1 <= e_i, then we take the step for sure (p = 1.0). If e_i+1 >
e+i, then
the probability of taking the step is based on the boltzmann distribution.
I
don't understand why multiple points(neighbors?) are sampled before taking
a step in our random walk.
I thought maybe it means, if n_tries = 20, then we try 20 points and take
the smallest e_i+1 if all 20 e_i+1 <= e_i. But then I don't understand how
GSL would handle cases where multiple e_i+1 > e_i, which leads me to
think I'm wrong about what n_tries means. Can anyone clear up for me
what n_tries function is?
Thanks in advance,
Sak S.
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Dipl.-Phys. Benjamin Winkel
Argelander Institute for Astronomy (AIfA)
University of Bonn
Auf dem Hügel 71, D-53121 Bonn, Germany
tel: +49 (0)228 73-3662
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http://www.astro.uni-bonn.de/~bwinkel
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