Model the spectral variation with a constant. More...

#include <ConstantSpectrum.h>

Inheritance diagram for casa::ConstantSpectrum:

Public Member Functions
	ConstantSpectrum ()
	The default constructor is the only one you really need as this class has no parameters! More...

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

virtual	~ConstantSpectrum ()
	The destructor does nothing. More...

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

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

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

virtual void	sampleStokes (const casacore::MFrequency &centerFrequency, casacore::Vector< casacore::Double > &iquv) const
	Original values returned. 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 > > &scale, const casacore::Vector< casacore::MFrequency::MVType > &frequencies, const casacore::MFrequency::Ref &refFrame) const
	original values are returned 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 ConstantSpectrum. 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 spectrum 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...

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

Model the spectral variation with a constant.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd
Test programs:: tConstantSpectrum
Demo programs:: dConstantSpectrum

Prerequisite

SpectralModel

Synopsis

This class models the spectral variation of a component as constant, ie. unchanging with frequency. It is the simplest possible model for spectral variation.

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.

Because the flux is constant with frequency the concept of a reference frequency is meaningless with this class. But it can still be accessed using the refFrequency and setRefFrequency. However changing its value will not affect the behaviour of this class.

This class does not have any parameters and the nParameters function will return zero. It is an error that will generate an exception (in Debug mode) to call the setParameters and parameters functions with anything other than a zero length vector.

The sample functions always return 1.0.

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

c := [type = 'constant',
frequency = [type = 'frequency',
refer = 'lsr',
m0 = [value = 1, unit = 'GHz']
]
]

The frequency field contains a record representation of a 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.

Example

Its hard to think of a good example for this class as it is basically does nothing! In this example the spectral variation of a component is set to to a constant value.

 SkyComponent myComp(...);
..\.
 if (myComp.spectrum().type() != ComponentType::CONSTANT_SPECTRUM) {
 myComp.spectrum() = ConstantSpectrum();
 }

Motivation

A ConstantSpectrum class is needed for users who are not interested in modelling any spectral variation in their components.

To Do

Nothing I hope!

Definition at line 128 of file ConstantSpectrum.h.

Constructor & Destructor Documentation

casa::ConstantSpectrum::ConstantSpectrum ( )

The default constructor is the only one you really need as this class has no parameters!

casa::ConstantSpectrum::ConstantSpectrum ( const ConstantSpectrum & other )

The copy constructor uses copy semantics.

virtual casa::ConstantSpectrum::~ConstantSpectrum ( )

virtual

The destructor does nothing.

Member Function Documentation

virtual SpectralModel* casa::ConstantSpectrum::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::ConstantSpectrum::convertUnit	(	casacore::String &	errorMessage,
		const casacore::RecordInterface &	record
	)

virtual

Convert the parameters of the spectrum to the specified units.

As a constant spectrum has no parameters this function does nothing and always returns true.

Implements casa::SpectralModel.

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

virtual

Implements casa::SpectralModel.

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

virtual

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

These functions define how a ConstantSpectrum 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::ConstantSpectrum::nParameters ( ) const

virtual

return the number of parameters.

There are no parameters for this spectral model. So calling setParameters or parameters with anything other than a zero length casacore::Vector will throw an exception (when compiled in debug mode).

Implements casa::SpectralModel.

virtual casacore::Bool casa::ConstantSpectrum::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.

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

The assignment operator uses copy semantics.

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

virtual

Implements casa::SpectralModel.

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

virtual

Return the scaling factor that indicates the flux is at the specified frequency assuming the flux at the reference frequency is one.

This function always returns one, as the spectrum is constant.

Implements casa::SpectralModel.

virtual void casa::ConstantSpectrum::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.

Implements casa::SpectralModel.

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

virtual

Original values returned.

Implements casa::SpectralModel.

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

virtual

original values are returned

Implements casa::SpectralModel.

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

virtual

Implements casa::SpectralModel.

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

virtual

Implements casa::SpectralModel.

virtual casacore::Bool casa::ConstantSpectrum::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::ConstantSpectrum::type ( ) const

virtual

return the actual spectral type.

This function always returns ComponentType::CONSTANT_SPECTRUM

Implements casa::SpectralModel.

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