# RedHat 9 (Linux i386) - man page for pdl::fit::gaussian (redhat section 3)

Gaussian(3)						User Contributed Perl Documentation					       Gaussian(3)

NAME
PDL::Fit::Gaussian - routines for fitting gaussians
DESCRIPTION
This module contains some custom gaussian fitting routines. These were developed in collaboration with Alison Offer, they do a reasonably robust job and are quite useful. Gaussian fitting is something I do a lot of, so I figured it was worth putting in my special code. Note this code is also used in the Karma package.
SYNOPSIS
use PDL::Fit::Gaussian; (\$cen, \$pk, \$fwhm, \$back, \$err, \$fit) = fitgauss1d(\$x, \$data); (\$pk, \$fwhm, \$back, \$err, \$fit) = fitgauss1dr(\$r, \$data);
FUNCTIONS
fitgauss1d Fit 1D Gassian to data piddle (\$cen, \$pk, \$fwhm2, \$back, \$err, \$fit) = fitgauss1d(\$x, \$data); (\$cen, \$pk, \$fwhm2, \$back, \$err, \$fit) = fitgauss1d(\$x, \$data); xval(n); data(n); [o]xcentre();[o]peak_ht(); [o]fwhm(); [o]background();int [o]err(); [o]datafit(n); [t]sig(n); [t]xtmp(n); [t]ytmp(n); [t]yytmp(n); [t]rtmp(n); Fit's a 1D Gaussian robustly free parameters are the centre, peak height, FWHM. The background is NOT fit, because I find this is generally unreliable, rather a median is determined in the 'outer' 10% of pixels (i.e. those at the start/end of the data piddle). The initial esti- mate of the FWHM is the length of the piddle/3, so it might fail if the piddle is too long. (This is non-robust anyway). Most data does just fine and this is a good default gaussian fitter. SEE ALSO: fitgauss1dr() for fitting radial gaussians fitgauss1dr Fit 1D Gassian to radial data piddle (\$pk, \$fwhm2, \$back, \$err, \$fit) = fitgauss1dr(\$r, \$data); (\$pk, \$fwhm2, \$back, \$err, \$fit) = fitgauss1dr(\$r, \$data); xval(n); data(n); [o]peak_ht(); [o]fwhm(); [o]background();int [o]err(); [o]datafit(n); [t]sig(n); [t]xtmp(n); [t]ytmp(n); [t]yytmp(n); [t]rtmp(n); Fit's a 1D radial Gaussian robustly free parameters are the peak height, FWHM. Centre is assumed to be X=0 (i.e. start of piddle). The background is NOT fit, because I find this is generally unreliable, rather a median is determined in the 'outer' 10% of pixels (i.e. those at the end of the data piddle). The initial estimate of the FWHM is the length of the piddle/3, so it might fail if the piddle is too long. (This is non-robust anyway). Most data does just fine and this is a good default gaussian fitter. SEE ALSO: fitgauss1d() to fit centre as well.
BUGS
May not converge for weird data, still pretty good!
AUTHOR
This file copyright (C) 1999, Karl Glazebrook (kgb@aaoepp.aao.gov.au), Gaussian fitting code by Alison Offer (aro@aaocbn.aao.gov.au). All rights reserved. There is no warranty. You are allowed to redistribute this software / documentation under certain conditions. For details, see the file COPYING in the PDL distribution. If this file is separated from the PDL distribution, the copyright notice should be included in the file. perl v5.8.0 2003-01-29 Gaussian(3)