LatticeTwoPtCorr.h

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// # LatticeTwoPtCorr.h: compute two-point correlation functions from a lattice
// # Copyright (C) 1997,1998,1999,2000,2001,2003
// # 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 LATTICES_LATTICETWOPTCORR_H
#define LATTICES_LATTICETWOPTCORR_H
 
// # Includes
#include <casacore/casa/aips.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
 
template <class T>
class MaskedLattice;
template <class T>
class Lattice;
class IPosition;
class LogIO;
class String;
 
// <summary>
// Compute two point auto-correlation functions from a lattice
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="yyyy/mm/dd" tests="" demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class="MaskedLattice">MaskedLattice</linkto>
// </prerequisite>
 
// <synopsis>
// This class allows you to compute two point correlation functions
// from lattices over planes of the specified two axes.
// At present, only autocorrelation is implemented and only
// the structure function is available.
//
// The structure function is
// <src>S(x,y) = < [lat(i,j) - lat(i+x,j+y)]**2 ></src>
// where x and y are absolute integer shifts (or lags).
// </synopsis>
// <example>
// <srcblock>
// </srcblock>
// </example>
 
// <todo asof="yyyy/mm/dd">
// <li> Add additional algorithms other than the structure function
// <li> Allow cross correlation algorithms as well as autocorrelation
// </todo>
 
template <class T>
class LatticeTwoPtCorr {
 public:
  enum Method {
 
    // Undefined
    UNDEFINED,
 
    // Structure Function
    STRUCTUREFUNCTION,
 
    // nMethods
    NMETHODS
  };
 
  // Default constructor
  LatticeTwoPtCorr() {}
 
  // Destructor
  ~LatticeTwoPtCorr() {}
 
  // Compute specified autocorrelation function for the planes of the given TWO axes.
  // If the output lattice has a mask, it will first be set to False (bad)
  // and then any output pixel with some contributing values will be set to
  // True (good).
  // <group>
  void autoCorrelation(MaskedLattice<T>& out, const MaskedLattice<T>& in, const IPosition& axes,
                       Method method, Bool showProgress = True) const;
  // </group>
 
  // Helper function to provide output lattice shape give the input shape
  // and the axes to find the structure function over.
  static IPosition setUpShape(const IPosition& inShape, const IPosition& axes);
 
  // Helper functions to convert method types to and from strings
  // <group>
  static Method fromString(const String& method);
  static String toString(Method method);
  // </group>
 
 private:
  // Function Pointer typedef
  typedef T (LatticeTwoPtCorr<T>::*FuncPtr)(T d1, T d2) const;
 
  // Do the iteration work
  void autoCorrelation(MaskedLattice<T>& out, const MaskedLattice<T>& in, const IPosition& axes,
                       FuncPtr, Bool showProgress) const;
 
  // Check Output lattice shape
  void check(LogIO& os, const MaskedLattice<T>& latOut, const MaskedLattice<T>& latIn,
             const IPosition& axes) const;
 
  // Compute structure function
  T structureFunction(T d1, T d2) const { return (d1 - d2) * (d1 - d2); }
};
 
}  // namespace casacore
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/lattices/LatticeMath/LatticeTwoPtCorr.tcc>
#endif  // # CASACORE_NO_AUTO_TEMPLATES
#endif