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/*=========================================================================
*
* Copyright NumFOCUS
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
#ifndef itkCrossHelper_h
#define itkCrossHelper_h
#include "itkNumericTraits.h"
namespace itk
{
/** \class Cross
* \brief Compute the cross product of two vectors of dimension 3,
* independently of the type of the values of vector's elements.
*
* FIXME: Strictly speaking, the Cross product should not return a Vector, but
* a CovariantVector, since it behaves differently under Affine
* Transformations.
*
* \ingroup ITKCommon
*/
template <typename TVector>
class CrossHelper
{
public:
using VectorType = TVector;
using ValueType = typename VectorType::ValueType;
static constexpr unsigned int Dimension = VectorType::Dimension;
/**
* \param[in] iU
* \param[in] iV
* \return \f$ \boldsymbol{iU} \cdot \boldsymbol{iV} \f$
*/
VectorType
operator()(const VectorType & iU, const VectorType & iV) const
{
VectorType oCross;
if (Dimension > 2)
{
oCross[0] = iU[1] * iV[2] - iV[1] * iU[2];
oCross[1] = iV[0] * iU[2] - iU[0] * iV[2];
oCross[2] = iU[0] * iV[1] - iV[0] * iU[1];
if (Dimension > 3)
{
for (unsigned int dim = 3; dim < Dimension; ++dim)
{
oCross[dim] = 0.0;
}
}
}
else
{
oCross.Fill(0.);
}
return oCross;
}
};
} // namespace itk
#endif
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