chebfit_v2.pro

NRAO GBTIDL
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SUMMARY: fields | routine DETAILS: routine

./contrib
chebfit_v2.pro

Last modification date:: Wed Sep 28 13:27:15 2016

Routine Summary 2 routines

function svdcheb(X, M)
svdcheb - chebyshev fitting function for svdfit
Used by chebfit_v2 in call to svdfit.

function chebfit_v2(x, y, deg, [yfit=variable], [rangex=variable], [merr=float/double])
chebfit_v2 - chebyshev polynomial fit to data
Do a chebyshev polynomial fit of order deg to the x,y data.

Routine Details

svdcheb

function svdcheb(X, M)

svdcheb - chebyshev fitting function for svdfit

Used by chebfit_v2 in call to svdfit.

Parameters

X
.

M
.

chebfit_v2

function chebfit_v2(x, y, deg, [yfit=variable], [rangex=variable], [merr=float/double])

chebfit_v2 - chebyshev polynomial fit to data

Do a chebyshev polynomial fit of order deg to the x,y data. Merr are the measurement errors (see idl svdfit routine). Return the coefs for the fit as well as the mapping of the xrange into [-1,1].

NOTE: The fitting function svdcheb() is contained in this file. If the routine gives an error that it cannot find svdcheb() just compile this routine explicitly (.compile chebfit_v2).

Contributed By: Karen O'Neil, NRAO-GB

Returns: coef[deg+1]. coefs from fit
Version: $Id$

Parameters

x
in, required
float/double independent variable

y
in, required
float/double measured dependent variable, same number of elements as x.

deg
in, required
integer degree of fit (ge 1)

Keywords

yfit
out, optional
variable fit evaluated at x locations.

rangex
out, optional
variable 2-element array giving min and max values of x used for fit. These were used to map the x-axis into [-1,1] for the fit.

merr
in, optional
float/double measurement errors for y, same number of elements as y. Default is uniform.

Produced by IDLdoc 1.6 on Wed Sep 28 13:27:47 2016

Parameters
x in, required float/double	independent variable
y in, required float/double	measured dependent variable, same number of elements as x.
deg in, required integer	degree of fit (ge 1)

Keywords
yfit out, optional variable	fit evaluated at x locations.
rangex out, optional variable	2-element array giving min and max values of x used for fit. These were used to map the x-axis into [-1,1] for the fit.
merr in, optional float/double	measurement errors for y, same number of elements as y. Default is uniform.