Fits and optionally subtracts the continuum in visibility spectra. More...

#include <VBContinuumSubtractor.h>

Public Member Functions
	VBContinuumSubtractor ()
	VBContinuumSubtractor (const Double lofreq, const Double hifreq)
	Construct it with the low and high frequencies used for scaling the frequencies in the polynomial.
	~VBContinuumSubtractor ()
void	init (const IPosition &shp, const uInt maxAnt, const uInt totnumchan, const Double lof, const Double hif)
	Set the # of correlations and fitorder from shp, the total number of input channels to look at (including masked ones!), and the low and high scaling frequencies.
Bool	initFromVBGA (VisBuffGroupAcc &vbga)
	Set the low and high frequencies, and #s of correlations, antennas, and channels from vbga.
void	fit (VisBuffGroupAcc &vbga, const Int fitorder, MS::PredefinedColumns whichcol, Cube< Complex > &coeffs, Cube< Bool > &coeffsOK, const Bool doInit=False, const Bool doResize=False, const Bool squawk=True)
	Makes the continuum estimate by fitting a frequency polynomial of order fitorder to the data in vbga.
Bool	apply (VisBuffer &vb, const MS::PredefinedColumns whichcol, const Cube< Complex > &coeffs, const Cube< Bool > &coeffsOK, const Bool doSubtraction=True, const Bool squawk=True)
	Apply the continuum estimate in coeffs (from fit) to vb.
Bool	areFreqsInBounds (VisBuffer &vb, const Bool squawk) const
	Returns whether or not vb's frequencies are within the bounds used for the continuum fit.
Int	getOrder () const
	These are provided for the calibration framework so that a VBContinuumSubtractor can be c'ted from a VisBuffGroupAcc, make a continuum fit, write its results to a caltable, destroyed, and then later another one can be c'ted from the caltable and apply the fit to a VisBuffer.
Double	getLowFreq () const
Double	getHighFreq () const
Int	getMaxAntNum () const
	the MS def'n v.2.
uInt	getTotNumChan () const
	The total number of input channels that will be looked at (including masked ones!)
void	setScalingFreqs (Double lof, Double hif)
	Low (lof) and high (hif) frequencies, in Hz, used for renormalizing frequencies in the polynomials.
void	setNAnt (const uInt nAnt)
	Set the maximum number of antennas (actually, 1 + the maximum antenna number).
void	setTotNumChan (const uInt tnc)
	Set the total number of input channels that will be looked at (including masked ones!)
void	resize (Cube< Complex > &coeffs, Cube< Bool > &coeffsOK) const
	A convenience function for prepping coeffs and coeffsOK to hold the polynomial coefficients and their validities.
Bool	checkSize (Cube< Complex > &coeffs, Cube< Bool > &coeffsOK) const
Double	calcFreqScale () const
Static Public Member Functions
static void	getMinMaxFreq (VisBuffer &vb, Double &minfreq, Double &maxfreq, const Bool initialize=True)
	Fills minfreq and maxfreq with the minimum and maximum frequencies (in Hz, acc.
Private Member Functions
VBContinuumSubtractor &	operator= (VBContinuumSubtractor &other)
	Disable default copying, and assignment.
Bool	doShapesMatch (VisBuffer &vb, LogIO &os, const Bool squawk=true) const
	Can the fit be applied to vb? If not and squawk is true, send a severe message to os.
uInt	hashFunction (const Int ant1, const Int ant2)
	Compute baseline (row) index in coeffs_p for (ant1, ant2).
Private Attributes
Int	fitorder_p
	VisBuffGroupAcc& vbga_p; // Holds the VisBuffers.
Double	lofreq_p
Double	hifreq_p
Double	midfreq_p
Double	freqscale_p
Int	maxAnt_p
uInt	nHashes_p
	used with the fits.
uInt	ncorr_p
uInt	totnumchan_p
PtrBlock< Vector< Bool > * >	chanmask_p

Detailed Description

Fits and optionally subtracts the continuum in visibility spectra.

Intended use:

Public interface

Review Status

Date Reviewed:: yyyy/mm/dd

Prerequisite

MeasurementSet

Etymology

This class's main aim is to subtract the continuum from VisBuffers.

Synopsis

Spectral line observations often contain continuum emission which is present in all channels (often with a small slope and curvature across the band). This class fits a polynomial to this continuum, and can return the continuum and/or line (continuum-subtracted) estimates as VisBuffers.

Example

      const Int fitorder = 4;                 // Careful!  High orders might
                                              // absorb power from the lines.
      MS inMS(fileName);
      Block<Int> sortcolumns;
      ROVisIter vi(inMS, sortcolumns, 0.0);
      VisBuffer cvb(vi);                         // Continuum estimate
      VisBuffer lvb(vi);                         // Line estimate
      VisBuffer vb(vi);
      for(vi.originChunks(); vi.moreChunks(); vi.nextChunk()){
        for(vi.origin(); vi.more(); ++vi){
          VBContinuumSubtractor contestor(vb, fitorder); // Continuum Estimator
   
          contestor.cont_est(cvb);             // Put continuum estimate into cvb.
          contestor.cont_subtracted(lvb);      // Put line estimate into lvb.
   
          // Do something with cvb and lvb..\.
        }
      }

Motivation

This class provides continuum fitting by polynomials with order >= 0, with a convenient interface for use by other classes in synthesis and msvis (i.e. calibration, imaging, and split).

Definition at line 95 of file VBContinuumSubtractor.h.

Constructor & Destructor Documentation

casa::VBContinuumSubtractor::VBContinuumSubtractor ( )

casa::VBContinuumSubtractor::VBContinuumSubtractor	(	const Double	lofreq,
		const Double	hifreq
	)

Construct it with the low and high frequencies used for scaling the frequencies in the polynomial.

casa::VBContinuumSubtractor::~VBContinuumSubtractor ( )

Member Function Documentation

Bool casa::VBContinuumSubtractor::apply	(	VisBuffer &	vb,
		const MS::PredefinedColumns	whichcol,
		const Cube< Complex > &	coeffs,
		const Cube< Bool > &	coeffsOK,
		const Bool	doSubtraction = `True`,
		const Bool	squawk = `True`
	)

Apply the continuum estimate in coeffs (from fit) to vb.

The affected column of vb is chosen by whichcol, which must be exactly one of MS::DATA, MS::MODEL_DATA, or MS::CORRECTED_DATA lest an exception will be thrown. If doSubtraction is True, vb becomes the line estimate. Otherwise it is replaced with the continuum estimate. Returns False if it detects an error, True otherwise. squawk=True increases the potential number of warnings sent to the logger.

Bool casa::VBContinuumSubtractor::areFreqsInBounds	(	VisBuffer &	vb,
		const Bool	squawk
	)		const

Returns whether or not vb's frequencies are within the bounds used for the continuum fit.

If not, and squawk is True, a warning will be sent to the logger. (Extrapolation is allowed, just not recommended.)

Double casa::VBContinuumSubtractor::calcFreqScale ( ) const [inline]

Definition at line 212 of file VBContinuumSubtractor.h.

References hifreq_p, and midfreq_p.

Referenced by setScalingFreqs().

Bool casa::VBContinuumSubtractor::checkSize	(	Cube< Complex > &	coeffs,
		Cube< Bool > &	coeffsOK
	)		const `[inline]`

Definition at line 202 of file VBContinuumSubtractor.h.

References fitorder_p, ncorr_p, nHashes_p, and casa::Cube< T >::shape().

Bool casa::VBContinuumSubtractor::doShapesMatch	(	VisBuffer &	vb,
		LogIO &	os,
		const Bool	squawk = `true`
	)		const `[private]`

Can the fit be applied to vb? If not and squawk is true, send a severe message to os.

void casa::VBContinuumSubtractor::fit	(	VisBuffGroupAcc &	vbga,
		const Int	fitorder,
		MS::PredefinedColumns	whichcol,
		Cube< Complex > &	coeffs,
		Cube< Bool > &	coeffsOK,
		const Bool	doInit = `False`,
		const Bool	doResize = `False`,
		const Bool	squawk = `True`
	)

Makes the continuum estimate by fitting a frequency polynomial of order fitorder to the data in vbga.

It sets the low and high frequencies used for scaling the frequencies in the polynomial to the min and max frequencies in vbga. Input: vbga, The data fitorder, e.g. 2 for a + bf + cf**2 doInit, if true call initFromVBGA(vbga) doResize if true set coeffs and coeffsOK to the right shape. Output (these will be resized): coeffs: Polynomial coefficients for the continuum, indexed by (corr, order, hash(ant1, ant2). coeffsOK: and whether or not they're usable.

Double casa::VBContinuumSubtractor::getHighFreq ( ) const [inline]

Definition at line 170 of file VBContinuumSubtractor.h.

References hifreq_p.

Double casa::VBContinuumSubtractor::getLowFreq ( ) const [inline]

Definition at line 169 of file VBContinuumSubtractor.h.

References lofreq_p.

Int casa::VBContinuumSubtractor::getMaxAntNum ( ) const [inline]

the MS def'n v.2.

Definition at line 172 of file VBContinuumSubtractor.h.

References maxAnt_p.

static void casa::VBContinuumSubtractor::getMinMaxFreq	(	VisBuffer &	vb,
		Double &	minfreq,
		Double &	maxfreq,
		const Bool	initialize = `True`
	)		`[static]`

Fills minfreq and maxfreq with the minimum and maximum frequencies (in Hz, acc.

to the MS def'n v.2) of vb (not the continuum fit!). If you want to get the extreme frequencies over a set of VisBuffers, set initialize to False and initialize minfreq and maxfreq yourself to DBL_MAX and -1.0, respectively.

Int casa::VBContinuumSubtractor::getOrder ( ) const [inline]

These are provided for the calibration framework so that a VBContinuumSubtractor can be c'ted from a VisBuffGroupAcc, make a continuum fit, write its results to a caltable, destroyed, and then later another one can be c'ted from the caltable and apply the fit to a VisBuffer.

Obviously it'd be safer and faster to use the same VBContinuumSubtractor for fitting and application, but the rest of CASA isn't ready for that yet (3/7/2011).

Definition at line 167 of file VBContinuumSubtractor.h.

References fitorder_p.

uInt casa::VBContinuumSubtractor::getTotNumChan ( ) const [inline]

The total number of input channels that will be looked at (including masked ones!)

Definition at line 176 of file VBContinuumSubtractor.h.

References totnumchan_p.

uInt casa::VBContinuumSubtractor::hashFunction	(	const Int	ant1,
		const Int	ant2
	)		`[inline, private]`

Compute baseline (row) index in coeffs_p for (ant1, ant2).

It ASSUMES that ant1 and ant2 are both <= maxAnt_p.

Definition at line 226 of file VBContinuumSubtractor.h.

References maxAnt_p.

void casa::VBContinuumSubtractor::init	(	const IPosition &	shp,
		const uInt	maxAnt,
		const uInt	totnumchan,
		const Double	lof,
		const Double	hif
	)

Set the # of correlations and fitorder from shp, the total number of input channels to look at (including masked ones!), and the low and high scaling frequencies.

Bool casa::VBContinuumSubtractor::initFromVBGA ( VisBuffGroupAcc & vbga )

Set the low and high frequencies, and #s of correlations, antennas, and channels from vbga.

Returns False if vbga is empty.

VBContinuumSubtractor& casa::VBContinuumSubtractor::operator= ( VBContinuumSubtractor & other ) [private]

Disable default copying, and assignment.