Quaternion.inl

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//
//
/*
    Copyright (C) 2000- 2005, Hammersmith Imanet Ltd
    SPDX-License-Identifier: Apache-2.0
    See STIR/LICENSE.txt for details
*/
 
START_NAMESPACE_STIR
 
template <typename coordT>
coordT
norm_squared(const Quaternion<coordT>& q)
{
  return square(q[1]) + square(q[2]) + square(q[3]) + square(q[4]);
}
 
template <typename coordT>
coordT
norm(const Quaternion<coordT>& q)
{
  return sqrt(norm_squared(q));
}
 
template <typename coordT>
coordT
Quaternion<coordT>::dot_product(const Quaternion<coordT>& q1, const Quaternion<coordT>& q2)
{
  return ((q1[1] * q2[1]) + (q1[2] * q2[2]) + (q1[3] * q2[3]) + (q1[4] * q2[4]));
}
 
template <typename coordT>
Quaternion<coordT>&
Quaternion<coordT>::operator*=(const Quaternion<coordT>& q)
{
  const Quaternion<coordT> tmp(*this);
  (*this)[1] = tmp[1] * q[1] - tmp[2] * q[2] - tmp[3] * q[3] - tmp[4] * q[4];
  (*this)[2] = tmp[1] * q[2] + tmp[2] * q[1] + tmp[3] * q[4] - tmp[4] * q[3];
  (*this)[3] = tmp[1] * q[3] + tmp[3] * q[1] + tmp[4] * q[2] - tmp[2] * q[4];
  (*this)[4] = tmp[1] * q[4] + tmp[4] * q[1] + tmp[2] * q[3] - tmp[3] * q[2];
 
  return *this;
}
 
template <typename coordT>
Quaternion<coordT>&
Quaternion<coordT>::operator*=(const coordT& a)
{
  for (int i = 1; i <= 4; i++)
    (*this)[i] *= a;
  return *this;
}
 
template <typename coordT>
Quaternion<coordT>
Quaternion<coordT>::operator*(const Quaternion& q) const
{
  Quaternion<coordT> tmp(*this);
  tmp *= q;
 
  return tmp;
}
 
template <typename coordT>
Quaternion<coordT>
Quaternion<coordT>::operator*(const coordT& a) const
{
  Quaternion<coordT> tmp(*this);
  tmp *= a;
  return tmp;
}
 
template <typename coordT>
Quaternion<coordT>&
Quaternion<coordT>::operator/=(const coordT& a)
{
  for (int i = 1; i <= 4; i++)
    (*this)[i] /= a;
  return *this;
}
template <typename coordT>
Quaternion<coordT>&
Quaternion<coordT>::operator/=(const Quaternion& q)
{
  const Quaternion<coordT> con_q(q[1], -q[2], -q[3], -q[4]);
  const coordT norm_squared = (square(q[1]) + square(q[2]) + square(q[3]) + square(q[4]));
  *this *= con_q;
  *this /= norm_squared;
 
  return *this;
}
 
template <typename coordT>
Quaternion<coordT>
Quaternion<coordT>::operator/(const Quaternion& q) const
{
  Quaternion<coordT> tmp(*this);
  tmp /= q;
  return tmp;
}
 
template <typename coordT>
Quaternion<coordT>
Quaternion<coordT>::operator/(const coordT& a) const
{
  Quaternion<coordT> tmp(*this);
  tmp /= a;
  return tmp;
}
 
template <typename coordT>
void
Quaternion<coordT>::neg_quaternion()
{
  (*this)[1] = -(*this)[1];
  (*this)[2] = -(*this)[2];
  (*this)[3] = -(*this)[3];
  (*this)[4] = -(*this)[4];
}
 
template <typename coordT>
void
Quaternion<coordT>::conjugate()
{
  //  (*this)[1] =(*this)[1];
  (*this)[2] = -(*this)[2];
  (*this)[3] = -(*this)[3];
  (*this)[4] = -(*this)[4];
}
 
template <typename coordT>
void
Quaternion<coordT>::normalise()
{
  const coordT n = norm(*this);
  (*this)[1] /= n;
  (*this)[2] /= n;
  (*this)[3] /= n;
  (*this)[4] /= n;
}
 
template <typename coordT>
void
Quaternion<coordT>::inverse()
{
  const coordT dp = norm_squared(*this);
  (*this)[1] = (*this)[1] / dp;
  (*this)[2] = -(*this)[2] / dp;
  (*this)[3] = -(*this)[3] / dp;
  (*this)[4] = -(*this)[4] / dp;
}
 
template <typename coordT>
Quaternion<coordT>
conjugate(const Quaternion<coordT>& q)
{
  Quaternion<coordT> tmp = q;
  tmp.conjugate();
  return tmp;
}
 
template <typename coordT>
Quaternion<coordT>
inverse(const Quaternion<coordT>& q)
{
  Quaternion<coordT> tmp = q;
  tmp.inverse();
  return tmp;
}
 
END_NAMESPACE_STIR