eigen/Eigen/src/Core/NumTraits.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra. Eigen itself is part of the KDE project.
//
// Copyright (C) 2006-2008 Benoit Jacob <jacob@math.jussieu.fr>
//
// Eigen is free software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the Free Software
// Foundation; either version 2 or (at your option) any later version.
//
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// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details.
//
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//
// As a special exception, if other files instantiate templates or use macros
// or functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
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#ifndef EIGEN_NUMTRAITS_H
#define EIGEN_NUMTRAITS_H

/** \class NumTraits
  *
  * \brief Holds some data about the various numeric (i.e. scalar) types allowed by Eigen.
  *
  * \param T the numeric type about which this class provides data. Recall that Eigen allows
  *          only the following types for \a T: \c int, \c float, \c double,
  *          \c std::complex<float>, \c std::complex<double>.
  *
  * The provided data consists of:
  * \li A typedef \a Real, giving the "real part" type of \a T. If \a T is already real,
  *     then \a Real is just a typedef to \a T. If \a T is \c std::complex<U> then \a Real
  *     is a typedef to \a U.
  * \li A typedef \a FloatingPoint, giving the "floating-point type" of \a T. If \a T is
  *     \c int, then \a FloatingPoint is a typedef to \c double. Otherwise, \a FloatingPoint
  *     is a typedef to \a T.
  * \li A static const bool \a IsComplex. It is equal to \c true if \a T is a \c std::complex
  *     type, and to false otherwise.
  * \li A static const bool \a HasFloatingPoint. It is equal to \c false if \a T is \c int,
  *     and to \c true otherwise.
  */
template<typename T> struct NumTraits;

template<> struct NumTraits<int>
{
  typedef int Real;
  typedef double FloatingPoint;
  static const bool IsComplex = false;
  static const bool HasFloatingPoint = false;
};

template<> struct NumTraits<float>
{
  typedef float Real;
  typedef float FloatingPoint;
  static const bool IsComplex = false;
  static const bool HasFloatingPoint = true;
};

template<> struct NumTraits<double>
{
  typedef double Real;
  typedef double FloatingPoint;
  static const bool IsComplex = false;
  static const bool HasFloatingPoint = true;
};

template<typename _Real> struct NumTraits<std::complex<_Real> >
{
  typedef _Real Real;
  typedef std::complex<_Real> FloatingPoint;
  static const bool IsComplex = true;
  static const bool HasFloatingPoint = NumTraits<Real>::HasFloatingPoint;
};

#endif // EIGEN_NUMTRAITS_H