SincFunction.h

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// # SincFunction.h: A one dimensional sin(x)/x
// # Copyright (C) 2002,2005
// # 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 SCIMATH_SINCFUNCTION_H
#define SCIMATH_SINCFUNCTION_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/scimath/Functionals/SincParam.h>
#include <casacore/scimath/Functionals/Function.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward declarations
 
// <summary> A one dimensional sin(x)/x
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="tFunctionHolder"
// demos="">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class="SincParam">SincParam</linkto>
//   <li> <linkto class="Function">Function</linkto>
// </prerequisite>
 
// <etymology>
// A 1-dimensional sinc function.
// </etymology>
 
// <synopsis>
// A <src>Sinc</src> is described by a height, a center and a width
// (halfwidth). The value is:
// <srcblock>
//      let y = (x-center)/width
//      height                              (x == center)
//      height*sin(pi*y)/(pi*y)             (x |= center)
// </srcblock>
// The parameters are enumerated by HEIGHT, CENTER and WIDTH. They have
// default values of (1, 0, 1).
// </synopsis>
//
// <example>
// <srcblock>
//    SincFunction<Double> sf(5.0, 25.0, 7);
//    sf(25);            // = 5.0
// </srcblock>
// </example>
 
// <templating arg=T>
//  <li> T should have standard numerical operators
// </templating>
 
// <thrown>
//    <li> AipsError if incorrect parameter number specified.
// </thrown>
//
 
template <class T>
class SincFunction : public SincParam<T> {
 public:
  // # Constructors
  //  Constructs the SincFunction, Defaults:
  //  height=1, center=0, width=1.
  //  <note role=warning> Could not use default arguments
  //  that worked both with gcc and IRIX </note>
  //  <group>
  SincFunction() : SincParam<T>() {}
  explicit SincFunction(const T &height) : SincParam<T>(height) {}
  SincFunction(const T &height, const T &center) : SincParam<T>(height, center) {}
  SincFunction(const T &height, const T &center, const T &width)
      : SincParam<T>(height, center, width) {}
  // </group>
 
  // Copy constructor (deep copy)
  // <group>
  SincFunction(const SincFunction<T> &other) : SincParam<T>(other) {}
  template <class W>
  SincFunction(const SincFunction<W> &other) : SincParam<T>(other) {}
  // </group>
 
  // Copy assignment (deep copy)
  SincFunction<T> &operator=(const SincFunction<T> &other) {
    SincParam<T>::operator=(other);
    return *this;
  }
 
  // Destructor
  virtual ~SincFunction() {}
 
  // # Operators
  //  Evaluate the Sinc at <src>x</src>.
  //  If a vector is used as the argument only its first element is used.
  //  <group>
  virtual T eval(typename Function<T>::FunctionArg x) const;
  // </group>
 
  // # Member functions
  //  Return a copy of this object from the heap. The caller is responsible
  //  for deleting this pointer.
  //  <group>
  virtual Function<T> *clone() const { return new SincFunction<T>(*this); }
  virtual Function<typename FunctionTraits<T>::DiffType> *cloneAD() const {
    return new SincFunction<typename FunctionTraits<T>::DiffType>(*this);
  }
  virtual Function<typename FunctionTraits<T>::BaseType> *cloneNonAD() const {
    return new SincFunction<typename FunctionTraits<T>::BaseType>(*this);
  }
  // </group>
 
  // # Make members of parent classes known.
 protected:
  using SincParam<T>::param_p;
 
 public:
  using SincParam<T>::nparameters;
  using SincParam<T>::CENTER;
  using SincParam<T>::WIDTH;
  using SincParam<T>::HEIGHT;
};
 
}  // namespace casacore
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/scimath/Functionals/SincFunction.tcc>
#endif  // # CASACORE_NO_AUTO_TEMPLATES
#endif