#ifndef vnl_cross_h_
#define vnl_cross_h_
//:
// \file
// Implements cross product for vectors.
// \author Amitha Perera
// \verbatim
//  Modifications
//   Oct.2002 - Amitha Perera - moved from vnl_vector.h
// \endverbatim

#include "vnl_vector.h"
#include "vnl_vector_fixed.h"
#include <cassert>
#ifdef _MSC_VER
#  include <vcl_msvc_warnings.h>
#endif
#include "vnl/vnl_export.h"

//: Compute the 2-D cross product
// \relatesalso vnl_vector
template <class T>
inline T
vnl_cross_2d(const vnl_vector<T> & v1, const vnl_vector<T> & v2)
{
  assert(v1.size() >= 2 && v2.size() >= 2);
  return v1[0] * v2[1] - v1[1] * v2[0];
}

//: Compute the 2-D cross product
// \relatesalso vnl_vector_fixed
template <class T>
inline T
vnl_cross_2d(const vnl_vector_fixed<T, 2> & v1, const vnl_vector_fixed<T, 2> & v2)
{
  return v1[0] * v2[1] - v1[1] * v2[0];
}

//: Compute the 2-D cross product
// \relatesalso vnl_vector
// \relatesalso vnl_vector_fixed
template <class T>
inline T
vnl_cross_2d(const vnl_vector_fixed<T, 2> & v1, const vnl_vector<T> & v2)
{
  assert(v2.size() == 2);
  return v1[0] * v2[1] - v1[1] * v2[0];
}

//: Compute the 2-D cross product
// \relatesalso vnl_vector
// \relatesalso vnl_vector_fixed
template <class T>
inline T
vnl_cross_2d(const vnl_vector<T> & v1, const vnl_vector_fixed<T, 2> & v2)
{
  assert(v1.size() == 2);
  return v1[0] * v2[1] - v1[1] * v2[0];
}

//: Compute the 3-D cross product
// \relatesalso vnl_vector
template <class T>
inline vnl_vector<T>
vnl_cross_3d(const vnl_vector<T> & v1, const vnl_vector<T> & v2)
{
  assert(v1.size() == 3 && v2.size() == 3);
  vnl_vector<T> result(3);
  result[0] = v1[1] * v2[2] - v1[2] * v2[1]; // work for both col/row
  result[1] = v1[2] * v2[0] - v1[0] * v2[2]; // representation
  result[2] = v1[0] * v2[1] - v1[1] * v2[0];
  return result;
}

//: Compute the 3-D cross product
// \relatesalso vnl_vector_fixed
template <class T>
inline vnl_vector_fixed<T, 3>
vnl_cross_3d(const vnl_vector_fixed<T, 3> & v1, const vnl_vector_fixed<T, 3> & v2)
{
  vnl_vector_fixed<T, 3> result;
  result[0] = v1[1] * v2[2] - v1[2] * v2[1]; // work for both col/row
  result[1] = v1[2] * v2[0] - v1[0] * v2[2]; // representation
  result[2] = v1[0] * v2[1] - v1[1] * v2[0];
  return result;
}

//: Compute the 3-D cross product
// \relatesalso vnl_vector
// \relatesalso vnl_vector_fixed
template <class T, unsigned int n>
inline vnl_vector_fixed<T, n>
vnl_cross_3d(const vnl_vector_fixed<T, n> & a, const vnl_vector<T> & b)
{
  return vnl_cross_3d(a.as_ref(), b);
}

//: Compute the 3-D cross product
// \relatesalso vnl_vector
// \relatesalso vnl_vector_fixed
template <class T, unsigned int n>
inline vnl_vector_fixed<T, n>
vnl_cross_3d(const vnl_vector<T> & a, const vnl_vector_fixed<T, n> & b)
{
  return vnl_cross_3d(a, b.as_ref());
}

#endif // vnl_cross_h_
