Models the spectral variation with a spectral index. More...

#include <TabularSpectrum.h>

Inheritance diagram for casa::TabularSpectrum:

Public Member Functions
	TabularSpectrum ()
	The default SpectralIndex has a reference frequency of 1 GHz in the LSR frame and a spectral index of zero. More...

	TabularSpectrum (const casacore::MFrequency &refFreq, const casacore::Vector< casacore::MFrequency::MVType > &freq, const casacore::Vector< Flux< casacore::Double > > &flux, const casacore::MFrequency::Ref &refFrame)
	Construct a Tabular values with I and f specified exponent. More...

	TabularSpectrum (const TabularSpectrum &other)
	The copy constructor uses copy semantics. More...

virtual	~TabularSpectrum ()
	The destructor does nothing special. More...

TabularSpectrum &	operator= (const TabularSpectrum &other)
	The assignment operator uses copy semantics. More...

virtual ComponentType::SpectralShape	type () const
	return the actual spectral type ie., ComponentType::TABULAR_SPECTRUM More...

virtual void	setRefFrequency (const casacore::MFrequency &newRefFreq)
	set/get the reference frequency More...

void	values (casacore::Vector< casacore::MFrequency::MVType > &freq, casacore::Vector< Flux< casacore::Double > > &flux) const
	set/get the Tabular values More...

void	setValues (const casacore::Vector< casacore::MFrequency::MVType > &frequencies, const casacore::Vector< Flux< casacore::Double > > &flux, const casacore::MFrequency::Ref &refFrame)

virtual casacore::Double	sample (const casacore::MFrequency &centerFrequency) const
	Return the scaling factor that indicates what proportion of the flux is at the specified frequency. More...

virtual void	sampleStokes (const casacore::MFrequency &centerFrequency, casacore::Vector< casacore::Double > &iquv) const
	return full casacore::Stokes version especially for models which have different frequency dependence for the casacore::Stokes param (1 or 4 elements) So as allow for fractional pol change and angle change of linear pol w.r.t frequency A a four casacore::Vector of original IQUV should be passed in and it will hold the return values More...

virtual void	sample (casacore::Vector< casacore::Double > &scale, const casacore::Vector< casacore::MFrequency::MVType > &frequencies, const casacore::MFrequency::Ref &refFrame) const
	Same as the previous function except that many frequencies can be sampled at once. More...

virtual void	sampleStokes (casacore::Vector< casacore::Vector< casacore::Double > > &iquv, const casacore::Vector< casacore::MFrequency::MVType > &frequencies, const casacore::MFrequency::Ref &refFrame) const
	So as allow for fractional pol change and angle change of linear pol w.r.t frequency casacore::Vector of four Vectors of original IQUV should be passed in and it will hold the return values Uitimately this math should really go in Flux and FluxRep to where a rotation of linear pol is allowed. More...

virtual SpectralModel *	clone () const
	Return a pointer to a copy of this object upcast to a SpectralModel object. More...

virtual casacore::uInt	nParameters () const
	return the number of parameters. More...

virtual void	setParameters (const casacore::Vector< casacore::Double > &newSpectralParms)

virtual casacore::Vector < casacore::Double >	parameters () const

virtual void	setErrors (const casacore::Vector< casacore::Double > &newSpectralErrs)

virtual casacore::Vector < casacore::Double >	errors () const

virtual casacore::Bool	fromRecord (casacore::String &errorMessage, const casacore::RecordInterface &record)
	These functions convert between a casacore::Record and a SpectralIndex. More...

virtual casacore::Bool	toRecord (casacore::String &errorMessage, casacore::RecordInterface &record) const
	Convert the class to an Record representation. More...

virtual casacore::Bool	convertUnit (casacore::String &errorMessage, const casacore::RecordInterface &record)
	Convert the parameters of the spectral index object to the specified units. More...

virtual casacore::Bool	ok () const
	casacore::Function which checks the internal data of this class for consistant values. More...

Public Member Functions inherited from casa::SpectralModel
virtual	~SpectralModel ()
	a virtual destructor is needed so that the actual destructor in the derived class will be used. More...

virtual const casacore::String &	ident () const
	Specify the identification of the record (e.g. More...

const casacore::MFrequency &	refFrequency () const

const casacore::Unit &	frequencyUnit () const
	get the frequency unit, and change the default frequency unit to the specified one. More...

void	convertFrequencyUnit (const casacore::Unit &freqUnit)

void	setRefFrequencyError (const casacore::Quantum< casacore::Double > &newRefFreqErr)
	set/get the error in the reference frequency. More...

const casacore::Quantum < casacore::Double > &	refFrequencyError () const

Public Member Functions inherited from casacore::RecordTransformable
virtual	~RecordTransformable ()
	The destructor must be virtual so that the destructor of derived classes is actually used. More...

virtual Bool	fromString (String &error, const String &inString)
	Initialise the class from a String representation. More...

Additional Inherited Members
Static Public Member Functions inherited from casa::SpectralModel
static ComponentType::SpectralShape	getType (casacore::String &errorMessage, const casacore::RecordInterface &record)
	Return the spectral shape that the supplied record represents. More...

Protected Member Functions inherited from casa::SpectralModel
	SpectralModel ()
	The constructors and assignment operator are protected as only derived classes should use them. More...

	SpectralModel (const casacore::MFrequency &refFreq, const casacore::Unit &=casacore::Unit("GHz"))

	SpectralModel (const SpectralModel &other)

SpectralModel &	operator= (const SpectralModel &other)

casacore::Double	refFreqInFrame (const casacore::MFrequency::Ref &frame) const
	Return the value refFrequency in the requested frame... More...

Static Protected Member Functions inherited from casa::SpectralModel
static casacore::Bool	badError (const casacore::Quantum< casacore::Double > &quantum)
	returns true if the quantum is not a non-negative quantity with units dimensionally identical to the Hz More...

Detailed Description

Models the spectral variation with a spectral index.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd
Test programs:: tSpectralIndex
Demo programs:: dSpectralModel

Prerequisite

SpectralModel

Synopsis

This class models the spectral variation of a component with measured values at given frequencies. The values are interpolated in betweenm

This class like the other spectral models becomes more useful when used through the SkyComponent class, which incorperates the flux and spatial variation of the emission, or through the ComponentList class, which handles groups of SkyComponent objects.

As with all classes derived from SpectralModel the basic operation of this class is to model the flux as a function of frequency. This class does not know what the flux is at the reference frequency. Instead the sample functions return factors that are used to scale the flux and calculate the amount of flux at a specified frequency.

Besides the reference frequency this class has one parameter; the spectral index. This parameter can be set & queried using the general purpose parameters functions or the class specific index functions.

This class also contains functions (toRecord & fromRecord) which perform the conversion between Records and SpectralIndex objects. These functions define how a SpectralIndex object is represented in glish. The format of the record that is generated and accepted by these functions is:

c = {'type' : 'tabular',
'frequency' : {'type' : 'frequency',
refer : 'lsr',
m0 :{'value' : [1,1.1, 1.2, 1.3, 1.4], 'unit' : 'GHz'}
},
'flux' : {'value' : [1.0,1.1, 1.2, 1.3, 1.4], 'unit' : 'Jy'}
}

The frequency field contains a record representation of a vector frequency measure and its format is defined in the Measures module. Its refer field defines the reference frame for the direction and the m0 field defines the value of the reference frequency. The parsing of the type field is case insensitive. The index field contains the spectral index.

Example

These examples are coded in the tSpectralModel.h file.

Example 1:

In this example a SpectralIndex object is created and used to calculate the flux at a number of frequencies.

SpectralIndex siModel;
siModel.setRefFrequency(casacore::MFrequency(casacore::Quantity(1.0, "GHz")));
siModel.setIndex(1.0, casacore::Stokes::I);  
siModel.setIndex(0.5, casacore::Stokes::Q);  
siModel.setIndex(0.5, casacore::Stokes::U);  
siModel.setIndex(-1.0, casacore::Stokes::V);
const Flux<casacore::Double> LBandFlux(1.0, 1.0, 1.0, 1.0);
const casacore::MVFrequency step(casacore::Quantity(100.0, "MHz"));
casacore::MVFrequency sampleFreq = siModel.refFrequency().getValue();
Flux<casacore::Double> sampleFlux;
cout << "Frequency\t I-Flux\t Q-Flux\t U-Flux\t V-Flux\n";
for (casacore::uInt i = 0; i < 11; i++) {
sampleFlux = LBandFlux.copy();
sampleFlux.convertPol(ComponentType::LINEAR);
sampleFlux.convertUnit(casacore::Unit("WU"));
siModel.sample(sampleFlux,
casacore::MFrequency(sampleFreq, siModel.refFrequency().getRef()));
cout << setprecision(3) << sampleFreq.get("GHz")
<< "\t\t " << sampleFlux.value(0u).re
<< "\t " << sampleFlux.value(1u).re
<< "\t " << sampleFlux.value(2u).re
<< "\t " << sampleFlux.value(3u).re
<< " " << sampleFlux.unit().getName() << endl;
sampleFreq += step;
}

Motivation

A Spectral Index frequency variation is the most widely used model in radio astronomy. In particular the NFRA package 'newstar' uses it extensively.

To Do

Nothing I hope

Definition at line 151 of file TabularSpectrum.h.

Constructor & Destructor Documentation

casa::TabularSpectrum::TabularSpectrum ( )

The default SpectralIndex has a reference frequency of 1 GHz in the LSR frame and a spectral index of zero.

As such it is no different from the ConstantSpectrum class (except slower).

casa::TabularSpectrum::TabularSpectrum	(	const casacore::MFrequency &	refFreq,
		const casacore::Vector< casacore::MFrequency::MVType > &	freq,
		const casacore::Vector< Flux< casacore::Double > > &	flux,
		const casacore::MFrequency::Ref &	refFrame
	)

Construct a Tabular values with I and f specified exponent.

casa::TabularSpectrum::TabularSpectrum ( const TabularSpectrum & other )

The copy constructor uses copy semantics.

virtual casa::TabularSpectrum::~TabularSpectrum ( )

virtual

The destructor does nothing special.

Member Function Documentation

virtual SpectralModel* casa::TabularSpectrum::clone ( ) const

virtual

Return a pointer to a copy of this object upcast to a SpectralModel object.

The class that uses this function is responsible for deleting the pointer. This is used to implement a virtual copy constructor.

Implements casa::SpectralModel.

virtual casacore::Bool casa::TabularSpectrum::convertUnit	(	casacore::String &	errorMessage,
		const casacore::RecordInterface &	record
	)

virtual

Convert the parameters of the spectral index object to the specified units.

Only one field of the supplied record is used, namely 'index'. This field is optional as the spectral index is a unitless quantity. If the index field is specified it must have the empty string as its value. This function always returns true unless the index field is specified and does not contain an empty string.

Implements casa::SpectralModel.

virtual casacore::Vector<casacore::Double> casa::TabularSpectrum::errors ( ) const

virtual

Implements casa::SpectralModel.

virtual casacore::Bool casa::TabularSpectrum::fromRecord	(	casacore::String &	errorMessage,
		const casacore::RecordInterface &	record
	)

virtual

These functions convert between a casacore::Record and a SpectralIndex.

These functions define how a SpectralIndex object is represented in glish and this is detailed in the synopsis above. These functions return false if the record is malformed and append an error message to the supplied string giving the reason.

Implements casa::SpectralModel.

virtual casacore::uInt casa::TabularSpectrum::nParameters ( ) const

virtual

return the number of parameters.

There is one parameter for this spectral model, namely the spectral index. So you supply a unit length vector when using these functions. Otherwise an exception (casacore::AipsError) may be thrown.

Implements casa::SpectralModel.

virtual casacore::Bool casa::TabularSpectrum::ok ( ) const

virtual

casacore::Function which checks the internal data of this class for consistant values.

Returns true if everything is fine otherwise returns false.

Reimplemented from casa::SpectralModel.

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

The assignment operator uses copy semantics.

virtual casacore::Vector<casacore::Double> casa::TabularSpectrum::parameters ( ) const

virtual

Implements casa::SpectralModel.

virtual casacore::Double casa::TabularSpectrum::sample ( const casacore::MFrequency & centerFrequency ) const

virtual

Return the scaling factor that indicates what proportion of the flux is at the specified frequency.

ie. if the centreFrequency argument is the reference frequency then this function will always return one. At other frequencies it will return a non-negative number.

Implements casa::SpectralModel.

virtual void casa::TabularSpectrum::sample	(	casacore::Vector< casacore::Double > &	scale,
		const casacore::Vector< casacore::MFrequency::MVType > &	frequencies,
		const casacore::MFrequency::Ref &	refFrame
	)		const

virtual

Same as the previous function except that many frequencies can be sampled at once.

The reference frame must be the same for all the specified frequencies. Uses a customised implementation for improved speed.

Implements casa::SpectralModel.

virtual void casa::TabularSpectrum::sampleStokes	(	const casacore::MFrequency &	centerFrequency,
		casacore::Vector< casacore::Double > &	stokesval
	)		const

virtual

return full casacore::Stokes version especially for models which have different frequency dependence for the casacore::Stokes param (1 or 4 elements) So as allow for fractional pol change and angle change of linear pol w.r.t frequency A a four casacore::Vector of original IQUV should be passed in and it will hold the return values

Implements casa::SpectralModel.

virtual void casa::TabularSpectrum::sampleStokes	(	casacore::Vector< casacore::Vector< casacore::Double > > &	stokesval,
		const casacore::Vector< casacore::MFrequency::MVType > &	frequencies,
		const casacore::MFrequency::Ref &	refFrame
	)		const

virtual

So as allow for fractional pol change and angle change of linear pol w.r.t frequency casacore::Vector of four Vectors of original IQUV should be passed in and it will hold the return values Uitimately this math should really go in Flux and FluxRep to where a rotation of linear pol is allowed.

Implements casa::SpectralModel.

virtual void casa::TabularSpectrum::setErrors ( const casacore::Vector< casacore::Double > & newSpectralErrs )

virtual

Implements casa::SpectralModel.

virtual void casa::TabularSpectrum::setParameters ( const casacore::Vector< casacore::Double > & newSpectralParms )

virtual

Implements casa::SpectralModel.

virtual void casa::TabularSpectrum::setRefFrequency ( const casacore::MFrequency & newRefFreq )

virtual

set/get the reference frequency

Reimplemented from casa::SpectralModel.

void casa::TabularSpectrum::setValues	(	const casacore::Vector< casacore::MFrequency::MVType > &	frequencies,
		const casacore::Vector< Flux< casacore::Double > > &	flux,
		const casacore::MFrequency::Ref &	refFrame
	)

virtual casacore::Bool casa::TabularSpectrum::toRecord	(	casacore::String &	error,
		casacore::RecordInterface &	outRecord
	)		const

virtual

Convert the class to an Record representation.

The input record may already contain fields and these fields may be silently overridden. New fields may be added to the input Record. If the transformation succeeds then the error String is unchanged and the function returns True. Otherwise the function returns False and appends an error message to the supplied String giving the reason why the conversion failed.

Implements casa::SpectralModel.

virtual ComponentType::SpectralShape casa::TabularSpectrum::type ( ) const

virtual

return the actual spectral type ie., ComponentType::TABULAR_SPECTRUM

Implements casa::SpectralModel.

void casa::TabularSpectrum::values	(	casacore::Vector< casacore::MFrequency::MVType > &	freq,
		casacore::Vector< Flux< casacore::Double > > &	flux
	)		const

set/get the Tabular values

Member Data Documentation

casacore::Vector<Flux<casacore::Double> > casa::TabularSpectrum::flux_p

private

Definition at line 243 of file TabularSpectrum.h.

casacore::MFrequency::Ref casa::TabularSpectrum::freqRef_p

private

Definition at line 241 of file TabularSpectrum.h.

casacore::Vector<casacore::Double> casa::TabularSpectrum::ival_p

private

Definition at line 244 of file TabularSpectrum.h.

casacore::Double casa::TabularSpectrum::maxFreq_p

private

Definition at line 247 of file TabularSpectrum.h.

casacore::Double casa::TabularSpectrum::minFreq_p

private

Definition at line 248 of file TabularSpectrum.h.

casacore::Vector<casacore::Double> casa::TabularSpectrum::qval_p

private

Definition at line 244 of file TabularSpectrum.h.

casacore::Double casa::TabularSpectrum::referenceFreq_p

private

Definition at line 246 of file TabularSpectrum.h.

casacore::Vector<casacore::Double> casa::TabularSpectrum::refVal_p

private

Definition at line 245 of file TabularSpectrum.h.

casacore::Vector<casacore::Double> casa::TabularSpectrum::tabFreqVal_p

private

Definition at line 242 of file TabularSpectrum.h.

casacore::Vector<casacore::Double> casa::TabularSpectrum::uval_p

private

Definition at line 244 of file TabularSpectrum.h.

casacore::Vector<casacore::Double> casa::TabularSpectrum::vval_p

private

Definition at line 244 of file TabularSpectrum.h.

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

casa/code/components/ComponentModels/TabularSpectrum.h

Private Attributes
casacore::MFrequency::Ref	freqRef_p

casacore::Vector < casacore::Double >	tabFreqVal_p

casacore::Vector< Flux < casacore::Double > >	flux_p

casacore::Vector < casacore::Double >	ival_p

casacore::Vector < casacore::Double >	qval_p

casacore::Vector < casacore::Double >	uval_p

casacore::Vector < casacore::Double >	vval_p

casacore::Vector < casacore::Double >	refVal_p

casacore::Double	referenceFreq_p

casacore::Double	maxFreq_p

casacore::Double	minFreq_p

Public Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Intended use:

Review Status

Prerequisite

Synopsis

Example

Example 1:

Motivation

To Do

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation