StokesConverter.h

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// # StokesConverter.h: convert any set of polarizations into any other one
// # Copyright (C) 1997,2001
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 of the License, or (at your
// # option) any later version.
// #
// # This library is distributed in the hope that it will be useful, but WITHOUT
// # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// # FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef MS_STOKESCONVERTER_H
#define MS_STOKESCONVERTER_H
 
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/Vector.h>
#include <casacore/casa/Arrays/Matrix.h>
#include <casacore/casa/BasicSL/Complex.h>
#include <casacore/measures/Measures/Stokes.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// StokesConverter converts any set of polarizations into any other one
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="yyyy/mm/dd" tests="tStokesConverter" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <a href="StokesConverter.html"> Stokes </a>
// </prerequisite>
//
// <etymology>
// StokesConverter is a class that converts Stokes Parameters
// </etymology>
//
// <synopsis>
// This class is used to convert polarizations from one system to
// another.
// First the conversion wanted is specified and then large blocks of data
// can be converted.
// <example>
// <srcblock>
// // create converter
//    StokesConverter sc;
//    Vector<Int> out(7),in(4);
// // set the input polarizations
//    in(0)=Stokes::RR;
//    in(1)=Stokes::LL;
//    in(2)=Stokes::RL;
//    in(3)=Stokes::LR;
// // set the required output
//    out(0)=Stokes::I;
//    out(1)=Stokes::Q;
//    out(2)=Stokes::U;
//    out(3)=Stokes::V;
//    out(4)=Stokes::Ptotal;
//    out(5)=Stokes::Pangle;
//    out(6)=Stokes::PFlinear;
// // initialize the conversion engine
//    sc.setConversion(out,in);
// // set up some test data
//    Vector<Complex> datain(4),dataout(7);
//    datain(0)=1.0;
//    datain(1)=0.9;
//    datain(2)=0.3;
//    datain(3)=0.2;
// // convert the data
//    sc.convert(dataout,datain);
// </srcblock>
// </example>
// </synopsis>
//
// <motivation>
// Polarization conversion is needed in various places. It makes sense to
// provide all conversion in one place.
// </motivation>
//
// <thrown>
//    <li>
//    <li>
// </thrown>
//
// <todo asof="1997/10/09">
//   <li> cope with incomplete input polarizations sensibly
//   <li> decide what to do about factor 2 between I and RR/LL,XX/YY etc.
// </todo>
 
class StokesConverter {
 public:
  // default constructor, does not set up a conversion
  StokesConverter();
 
  // Set up a conversion from in to out.
  // The in and out vectors contain a list of polarization present/wanted
  // in that order. The in vector should match the data to convert.
  // (CORR_TYPE column in SPECTRAL_WINDOW table contains this info)
  // The rescale option will correct for crosscorrelation data that
  // has been scaled to the level Stokes I (common practice
  // in radioastronomy: even though officially I=XX+YY, in practice
  // we need to do I=(XX+YY)/2, set rescale to True to do the latter).
  StokesConverter(const Vector<Int>& out, const Vector<Int>& in, Bool rescale = False);
 
  // desctructor
  ~StokesConverter();
 
  // Copy constructor
  StokesConverter(const StokesConverter& other);
 
  // Assignment,
  StokesConverter& operator=(const StokesConverter& other);
 
  // Change or Set the conversion. Arguments are the same as for
  // constructor above.
  void setConversion(const Vector<Int>& out, const Vector<Int>& in, Bool rescale = False);
 
  // convert data, first dimension of input must match
  // that of the input conversion vector used to set up the conversion.
  // Output is resized as needed.
  void convert(Array<Complex>& out, const Array<Complex>& in) const;
 
  // convert flags, first dimension of input must match
  // that of the input conversion vector used to set up the conversion.
  // Output is resized as needed. All output depending on a flagged input
  // will be flagged.
  void convert(Array<Bool>& out, const Array<Bool>& in) const;
 
  // convert weights, first dimension of input must match
  // that of the input conversion vector used to set up the conversion.
  // Output is resized as needed.
  // Set sigma to True when converting sigma's using this routine.
  void convert(Array<Float>& out, const Array<Float>& in, Bool sigma = False) const;
 
  // invert flags, first dimension of input must match
  // that of the output conversion vector used to set up the conversion.
  // Output is resized as needed. All output depending on a flagged input
  // will be flagged. This does the inverse operation of convert, allowing
  // flagging of converted data to be transferred back to the original data.
  void invert(Array<Bool>& out, const Array<Bool>& in) const;
 
 protected:
  // initialize the polarization conversion matrix
  void initConvMatrix();
 
 private:
  Vector<Int> in_p, out_p;
  Bool rescale_p;
  // # mutable because operator Matrix(Slice,Slice) doesn't have const version
  mutable Matrix<Complex> conv_p;
  mutable Matrix<Complex> iquvConv_p;
  Bool doIQUV_p;
  Matrix<Bool> flagConv_p;
  Matrix<Float> wtConv_p;
  Matrix<Complex> polConv_p;
};
 
}  // namespace casacore
 
#endif