Gaussian(n)    User Contributed Perl Documentation    Gaussian(n)



NAME
       PDL::Fit::Gaussian - routines for fitting gaussians

DESCRIPTION
       This module contains some custom gaussian fitting rou-
       tines.  These were developed in collaboration with Alison
       Offer, they do a reasonably robust job and are quite use-
       ful.

       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(l); data(a); [o]xcentre();[o]peak_ht(); [o]fwhm();
       [o]background();int [o]err(); [o]datafit(t); [t]sig(g);
       [t]xtmp(p); [t]ytmp(p); [t]yytmp(p); [t]rtmp(p);

       Fit's a 1D Gaussian robustly free parameters are the cen-
       tre, 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(l); data(a); [o]peak_ht(); [o]fwhm(); [o]back-
       ground();int [o]err(); [o]datafit(t); [t]sig(g);
       [t]xtmp(p); [t]ytmp(p); [t]yytmp(p); [t]rtmp(p);

       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 soft-
       ware / 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 v5.6.1                 2002-04-08                Gaussian(n)