Get an initial estimate for spectral lines. More...

#include <SpectralEstimate.h>

Public Member Functions
	SpectralEstimate (const casacore::uInt maxpar=MAXPAR)
	Default constructor creates a default estimator (default max number of components to be found is 200) with the given maximum number of components that will be found. More...

	SpectralEstimate (const casacore::Double rms, const casacore::Double cutoff=0.0, const casacore::Double minsigma=0.0, const casacore::uInt maxpar=MAXPAR)
	Create an estimator with the given maximum number of possible elements. More...

	SpectralEstimate (const SpectralEstimate &other)
	Copy constructor (deep copy) More...

	~SpectralEstimate ()
	Destructor. More...

SpectralEstimate &	operator= (const SpectralEstimate &other)
	Assignment (copy semantics) More...

template<class MT >
const SpectralList &	estimate (const casacore::Vector< MT > &ordinate, casacore::Vector< MT > *der=0)
	Generate the estimates for a profile and return the list found. More...

template<class MT >
const SpectralList &	estimate (const casacore::Vector< MT > &abcissa, const casacore::Vector< MT > &ordinate)

const SpectralList &	list () const
	Return the list found. More...

void	setRMS (const casacore::Double rms=0.0)
	Set estimation parameters. More...

void	setCutoff (const casacore::Double cutoff=0.0)
	Set the amplitude cutoff for valid estimate (forced to max(0,cutoff)) More...

void	setMinSigma (const casacore::Double minsigma=0.0)
	Set the minimum width allowed (forced to max(0,minsigma)) More...

void	setQ (const casacore::uInt q=2)
	Set the number of points consider at each side of test point (i.e. More...

void	setRegion (const casacore::Int lo, const casacore::Int hi)
	Set a region [lo,hi] over which to estimate. More...

void	setWindowing (const casacore::Bool win=false)
	Do you want to look in an automatically determined window with signal? Default is false, meaning the full (possibly regioned) profile. More...

void	setMaxN (const casacore::uInt maxpar=MAXPAR)
	Set the maximum number of estimates to find (forced to >=1; 200 default) More...

Static Public Attributes
static const casacore::uInt	MAXPAR
	Default maximum number of components to be found. More...

Private Member Functions
template<class MT >
casacore::uInt	window (const casacore::Vector< MT > &prof)
	Get the window or the total spectrum. More...

template<class MT >
void	findc2 (const casacore::Vector< MT > &prof)
	Get the second derivatives. More...

template<class MT >
void	findga (const casacore::Vector< MT > &prof)
	Find the Gaussians. More...

template<class MT >
GaussianSpectralElement	convertElement (const casacore::Vector< MT > &abcissa, const GaussianSpectralElement &el) const
	Convert the parameters of the components in the list from pixel-based indices to the given abcissa-vector space. More...

Private Attributes
casacore::Bool	useWindow_p
	Use window search. More...

casacore::Double	rms_p
	rms estimate in profile More...

casacore::Double	cutoff_p
	Source cutoff amplitude. More...

casacore::Int	windowLow_p
	Window low and end value. More...

casacore::Int	windowEnd_p

casacore::Int	regionLow_p
	Region low and high value. More...

casacore::Int	regionEnd_p

casacore::Int	q_p
	Smoothing parameter. More...

casacore::Double	a_p
	Internal cashing of calculated values based on q. More...

casacore::Double	b_p

casacore::Double	sigmin_p
	The minimum Gaussian width. More...

casacore::Double *	deriv_p
	The second derivatives. More...

SpectralList	slist_p
	The list of components. More...

casacore::uInt	lprof_p
	The length of the current profile being estimated. More...

Detailed Description

Get an initial estimate for spectral lines.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd
Test programs:: tSpectralFit

Prerequisite

SpectralFit class

Etymology

From spectral line and estimate

Synopsis

The SpectralEstimate class obtains an initial guess for spectral components. The current implementation uses the entire profile as signal region, or can set a window to be searched around the highest peak automatically. A window can also be set manually. The second derivative of the profile in the signal region is calculated by fitting a second degree polynomal. The smoothing parameter Q determines the number of points used for this (=2*Q+1). The gaussians can then be estimated as described by Schwarz, 1968, Bull.Astr.Inst.Netherlands, Volume 19, 405.

The elements guessed can be used in the SpectralFit class.

The default type found is a Gaussian, defined as:

AMPL.exp[ -(x-CENTER)<sup>2</sup>/2 SIGMA<sup>2</sup>]

The parameter estimates are returned in units of zero-based pixel indices.

Example

Motivation

To have an automatic method to find spectral lines

To Do

find a way to get to absorption lines as well
add more estimation options

Definition at line 99 of file SpectralEstimate.h.

Constructor & Destructor Documentation

casa::SpectralEstimate::SpectralEstimate ( const casacore::uInt maxpar = MAXPAR )

explicit

Default constructor creates a default estimator (default max number of components to be found is 200) with the given maximum number of components that will be found.

A value of zero will indicate an unlimited number.

casa::SpectralEstimate::SpectralEstimate	(	const casacore::Double	rms,
		const casacore::Double	cutoff = `0.0`,
		const casacore::Double	minsigma = `0.0`,
		const casacore::uInt	maxpar = `MAXPAR`
	)

explicit

Create an estimator with the given maximum number of possible elements.

A value of zero will indicate an unlimited number. Construct with a given rms in profiles, a cutoff for amplitudes found, and a minimum width. Cutoff and minsigma default to 0.0, maximum size of list produced to 200.

casa::SpectralEstimate::SpectralEstimate ( const SpectralEstimate & other )

Copy constructor (deep copy)

casa::SpectralEstimate::~SpectralEstimate ( )

Destructor.

Member Function Documentation

template<class MT >

GaussianSpectralElement casa::SpectralEstimate::convertElement	(	const casacore::Vector< MT > &	abcissa,
		const GaussianSpectralElement &	el
	)		const

private

Convert the parameters of the components in the list from pixel-based indices to the given abcissa-vector space.

template<class MT >

const SpectralList& casa::SpectralEstimate::estimate	(	const casacore::Vector< MT > &	ordinate,
		casacore::Vector< MT > *	der = `0`
	)

Generate the estimates for a profile and return the list found.

The first function returns component parameters in units of pixel indices. The second function calls the first and then converts to the specified abcissa space (the supplied vector must be monotonic); if the pixel-based center is out of range of the supplied abcissa vector the conversion is done via extrapolation. The der pointer is meant for debugging, and can return the derivative profile. The second function throws an AipsError if the vectors are not the same length.

template<class MT >

const SpectralList& casa::SpectralEstimate::estimate	(	const casacore::Vector< MT > &	abcissa,
		const casacore::Vector< MT > &	ordinate
	)

template<class MT >

void casa::SpectralEstimate::findc2 ( const casacore::Vector< MT > & prof )

private

Get the second derivatives.

template<class MT >

void casa::SpectralEstimate::findga ( const casacore::Vector< MT > & prof )

private

Find the Gaussians.

const SpectralList& casa::SpectralEstimate::list ( ) const

inline

Return the list found.

Definition at line 152 of file SpectralEstimate.h.

References slist_p.

SpectralEstimate& casa::SpectralEstimate::operator= ( const SpectralEstimate & other )

Assignment (copy semantics)

void casa::SpectralEstimate::setCutoff ( const casacore::Double cutoff = 0.0 )

Set the amplitude cutoff for valid estimate (forced to max(0,cutoff))

void casa::SpectralEstimate::setMaxN ( const casacore::uInt maxpar = MAXPAR )

Set the maximum number of estimates to find (forced to >=1; 200 default)

void casa::SpectralEstimate::setMinSigma ( const casacore::Double minsigma = 0.0 )

Set the minimum width allowed (forced to max(0,minsigma))

void casa::SpectralEstimate::setQ ( const casacore::uInt q = 2 )

Set the number of points consider at each side of test point (i.e.

a width of 2q+1 is taken). Default internally is 2; max(1,q) taken.

void casa::SpectralEstimate::setRegion	(	const casacore::Int	lo,
		const casacore::Int	hi
	)

Set a region [lo,hi] over which to estimate.

Lo and hi are given as zero-based vector indices.

void casa::SpectralEstimate::setRMS ( const casacore::Double rms = 0.0 )

Set estimation parameters.

Set the profile's estimated rms (forced to abs(rms))

void casa::SpectralEstimate::setWindowing ( const casacore::Bool win = false )

Do you want to look in an automatically determined window with signal? Default is false, meaning the full (possibly regioned) profile.

template<class MT >

casacore::uInt casa::SpectralEstimate::window ( const casacore::Vector< MT > & prof )

private

Get the window or the total spectrum.

Member Data Documentation

casacore::Double casa::SpectralEstimate::a_p

private

Internal cashing of calculated values based on q.

Definition at line 197 of file SpectralEstimate.h.

casacore::Double casa::SpectralEstimate::b_p

private

Definition at line 198 of file SpectralEstimate.h.

casacore::Double casa::SpectralEstimate::cutoff_p

private

Source cutoff amplitude.

Definition at line 182 of file SpectralEstimate.h.

casacore::Double* casa::SpectralEstimate::deriv_p

private

The second derivatives.

Definition at line 203 of file SpectralEstimate.h.

casacore::uInt casa::SpectralEstimate::lprof_p

private

The length of the current profile being estimated.

Definition at line 207 of file SpectralEstimate.h.

const casacore::uInt casa::SpectralEstimate::MAXPAR

static

Default maximum number of components to be found.

Definition at line 103 of file SpectralEstimate.h.

casacore::Int casa::SpectralEstimate::q_p

private

Smoothing parameter.

I.e. 2q+1 points are taken

Definition at line 194 of file SpectralEstimate.h.

casacore::Int casa::SpectralEstimate::regionEnd_p

private

Definition at line 191 of file SpectralEstimate.h.

casacore::Int casa::SpectralEstimate::regionLow_p

private

Region low and high value.

Definition at line 190 of file SpectralEstimate.h.

casacore::Double casa::SpectralEstimate::rms_p

private

rms estimate in profile

Definition at line 180 of file SpectralEstimate.h.

casacore::Double casa::SpectralEstimate::sigmin_p

private

The minimum Gaussian width.

Definition at line 201 of file SpectralEstimate.h.

SpectralList casa::SpectralEstimate::slist_p

private

The list of components.

Definition at line 205 of file SpectralEstimate.h.

Referenced by list().

casacore::Bool casa::SpectralEstimate::useWindow_p

private

Use window search.

Definition at line 178 of file SpectralEstimate.h.

casacore::Int casa::SpectralEstimate::windowEnd_p

private

Definition at line 186 of file SpectralEstimate.h.

casacore::Int casa::SpectralEstimate::windowLow_p

private

Window low and end value.

Definition at line 185 of file SpectralEstimate.h.

The documentation for this class was generated from the following file:

casa/code/components/SpectralComponents/SpectralEstimate.h

Public Member Functions

Static Public Attributes

Private Member Functions

Private Attributes

Detailed Description

Intended use:

Review Status

Prerequisite

Etymology

Synopsis

Example

Motivation

To Do

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation