Gaussian(3) User Contributed Perl Documentation Gaussian(3)NAMEPDL::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.
Note it is not clear to me that this code is fully debugged. The reason
I say that is because I tried using the internal linear eqn solving C
routines called elsewhere and they were giving erroneous results. So
steal from this code with caution! However it does give good fits to
reasonable looking gaussians and tests show correct parameters.
KGB 29/Oct/2002
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, $data);
xval(n); data(n); [o]xcentre();[o]peak_ht(); [o]fwhm();
[o]background();int [o]err(); [o]datafit(n); [t]sig(n); [t]xtmp(n);
[t]ytmp(n); [t]yytmp(n); [t]rtmp(n);
Fit's a 1D Gaussian robustly free parameters are the centre, peak
height, FWHM. The background is NOT fit, because I find this is
generally unreliable, rather a median is determined in the 'outer' 10%
of pixels (i.e. those at the start/end of the data piddle). The initial
estimate of the FWHM is the length of the piddle/3, so it might fail if
the piddle is too long. (This is non-robust anyway). Most data does
just fine and this is a good default gaussian fitter.
SEE ALSO: fitgauss1dr() for fitting radial gaussians
fitgauss1dr
Fit 1D Gassian to radial data piddle
($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 v5.10.0 2008-08-29 Gaussian(3)
