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.\" ========================================================================
.\"
.IX Title "Algorithm::SpiralSearch 3"
.TH Algorithm::SpiralSearch 3 "2008-11-24" "perl v5.22.0" "User Contributed Perl Documentation"
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.SH "NAME"
Algorithm::SpiralSearch \- Function Optimization of Two Parameters
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use Algorithm::SpiralSearch;
\&
\&  my $lbx   = 0;
\&  my $ubx   = 1000;
\&  my $lby   = 0;
\&  my $uby   = 1000;
\&  my $iters = 50;
\&  my ($x, $y) = spiral_search($lbx, $ubx, $lby, $uby, $iters, \e&f, \*(AqMAX\*(Aq);
\&
\&  sub f {
\&    my ($p1, $p2) = @_;
\&    my $ret = simulator($p1, $p2, ...);
\&    return $ret;
\&  }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
A spiral search is a method used to optimize a two-parameter, relatively,
well-behaved function. Boundary conditions, the maximum number of iterations, a
reference to a function, and an indicator to maximize or minimize the function
are passed to the spiral_search function.  \fIspiral_search()\fR returns the optimal
point in the function passed to it.  It's an elegant optimization algorithm, but
is not well-suited for most applications. \s-1SETI\s0 uses the spiral search in huntingfor strong radio signals. Spiral search is most effective in situations where
function evaluations are expensive and where there's a small amount of random
noise within the search space. The algorithm is of order O(n).
.SH "METHODS"
.IX Header "METHODS"
.SS "Search Methods"
.IX Subsection "Search Methods"
\&\fBspiral_search($lowerBound_x, \f(CB$upperBound_x\fB, \f(CB$lowerBound_y\fB, \f(CB$upperBound_y\fB,
   \f(CB$iterations\fB, \e&function, \f(CB$MAX_or_MIN\fB)\fR
.PP
Initiates the spiral search. The first four parameters define the search space
plane. Spiral search is of order O(n), so the number of iterations defines how
many refinements the algorithm should take into account.  The greater the numberof iterations, the more accurate the findings.
.PP
The sixth parameter should be a reference to a function for which the parameters
will be plugged into. This function should return only one value \- a scalar
output indicative of the accuracy of the inputs. The last input parameter shouldbe either one of the two strings '\s-1MAX\s0' or '\s-1MIN\s0', each corresponding to how
spiral_search will optimize its given function. spiral_search returns a pair of
parameters that are approximately optimal with respect to the given function.
.SH "AUTHOR"
.IX Header "AUTHOR"
Sean Mostafavi, <seanm@undersea.net>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright (C) 2006 by Sean Mostafavi
.PP
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself, either Perl version 5.8.5 or, at your option, anylater version of Perl 5 you may have available.