norm.h

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//
//
/*
    Copyright (C) 2003- 2005, Hammersmith Imanet Ltd
    This file is part of STIR.

    SPDX-License-Identifier: Apache-2.0

    See STIR/LICENSE.txt for details
*/

#ifndef __stir_numerics_norm_H__
#define __stir_numerics_norm_H__

#include "stir/common.h"
#include <complex>
#include <cmath>
#ifdef BOOST_NO_STDC_NAMESPACE
namespace std
{
using ::fabs;
}
#endif

START_NAMESPACE_STIR

template <int num_dimensions, class elemT>
class Array;



// specialisations for complex numbers are in .inl file for clarity of this file.
template <typename T>
struct NormSquared
{
  double operator()(T x) const { return static_cast<double>(x) * x; }
};


template <typename elemT>
inline double
norm_squared(const elemT t)
{
  return NormSquared<elemT>()(t);
}


template <typename elemT>
inline double
norm(const elemT t)
{
  return sqrt(norm_squared(t));
}

// 2 overloads to avoid doing sqrt(t*t)
inline double
norm(const double t)
{
  return std::fabs(t);
}

inline double
norm(const float t)
{
  return std::fabs(t);
}


template <class Iter>
inline double norm_squared(Iter begin, Iter end);


template <class Iter>
inline double norm(Iter begin, Iter end);


template <class elemT>
inline double norm(const Array<1, elemT>& v1);


template <class elemT>
inline double norm_squared(const Array<1, elemT>& v1);


END_NAMESPACE_STIR

#include "stir/numerics/norm.inl"

#endif