89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
/* ----------------------------------------------------------------------------
|
|
|
|
* GTSAM Copyright 2010, Georgia Tech Research Corporation,
|
|
* Atlanta, Georgia 30332-0415
|
|
* All Rights Reserved
|
|
* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
|
|
|
|
* See LICENSE for the license information
|
|
|
|
* -------------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Tensor3.h
|
|
* @brief Rank 3 tensors based on http://www.gps.caltech.edu/~walter/FTensor/FTensor.pdf
|
|
* Created on: Feb 10, 2010
|
|
* @author: Frank Dellaert
|
|
*/
|
|
|
|
#pragma once
|
|
#include <gtsam/geometry/tensors.h>
|
|
|
|
namespace tensors {
|
|
|
|
/** Rank 3 Tensor */
|
|
template<int N1, int N2, int N3>
|
|
class Tensor3 {
|
|
Tensor2<N1, N2> T[N3];
|
|
|
|
public:
|
|
|
|
/** default constructor */
|
|
Tensor3() {
|
|
}
|
|
|
|
/** construct from data */
|
|
Tensor3(const double data[N3][N2][N1]) {
|
|
for (int k = 0; k < N3; k++)
|
|
T[k] = data[k];
|
|
}
|
|
|
|
/** construct from expression */
|
|
template<class A, char I, char J, char K>
|
|
Tensor3(const Tensor3Expression<A, Index<N1, I> , Index<N2, J> , Index<N3,
|
|
K> >& a) {
|
|
for (int k = 0; k < N3; k++)
|
|
T[k] = a(k);
|
|
}
|
|
|
|
double operator()(int i, int j, int k) const {
|
|
return T[k](i, j);
|
|
}
|
|
|
|
/** convert to expression */
|
|
template<char I, char J, char K> Tensor3Expression<Tensor3, Index<N1, I> ,
|
|
Index<N2, J> , Index<N3, K> > operator()(const Index<N1, I>& i,
|
|
const Index<N2, J>& j, const Index<N3, K>& k) {
|
|
return Tensor3Expression<Tensor3, Index<N1, I> , Index<N2, J> , Index<N3,
|
|
K> > (*this);
|
|
}
|
|
|
|
/** convert to expression */
|
|
template<char I, char J, char K> Tensor3Expression<const Tensor3, Index<N1, I> ,
|
|
Index<N2, J> , Index<N3, K> > operator()(const Index<N1, I>& i,
|
|
const Index<N2, J>& j, const Index<N3, K>& k) const {
|
|
return Tensor3Expression<const Tensor3, Index<N1, I> , Index<N2, J> , Index<N3,
|
|
K> > (*this);
|
|
}
|
|
}; // Tensor3
|
|
|
|
/** Rank 3 permutation tensor */
|
|
struct Eta3 {
|
|
|
|
/** calculate value. TODO: wasteful to actually use this */
|
|
double operator()(int i, int j, int k) const {
|
|
return ((j - i) * (k - i) * (k - j)) / 2;
|
|
}
|
|
|
|
/** create expression */
|
|
template<char I, char J, char K> Tensor3Expression<Eta3, Index<3, I> ,
|
|
Index<3, J> , Index<3, K> > operator()(const Index<3, I>& i,
|
|
const Index<3, J>& j, const Index<3, K>& k) const {
|
|
return Tensor3Expression<Eta3, Index<3, I> , Index<3, J> , Index<3, K> > (
|
|
*this);
|
|
}
|
|
|
|
}; // Eta
|
|
|
|
} // namespace tensors
|