85 lines
1.8 KiB
C++
85 lines
1.8 KiB
C++
/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010, Georgia Tech Research Corporation,
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* Atlanta, Georgia 30332-0415
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* All Rights Reserved
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* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
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* See LICENSE for the license information
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* -------------------------------------------------------------------------- */
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/**
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* @file Tensor2.h
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* @brief Rank 2 Tensor based on http://www.gps.caltech.edu/~walter/FTensor/FTensor.pdf
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* @date Feb 10, 2010
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* @author Frank Dellaert
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*/
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#pragma once
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#include <gtsam/geometry/tensors.h>
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namespace tensors {
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/**
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* Rank 2 Tensor
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* @addtogroup tensors
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* \nosubgrouping
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*/
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template<int N1, int N2>
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class Tensor2 {
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protected:
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Tensor1<N1> T[N2]; ///< Storage
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public:
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/// @name Standard Constructors
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/// @{
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/** default constructor */
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Tensor2() {
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}
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/// construct from data - expressed in row major form
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Tensor2(const double data[N2][N1]) {
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for (int j = 0; j < N2; j++)
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T[j] = Tensor1<N1> (data[j]);
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}
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/** construct from expression */
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template<class A, char I, char J>
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Tensor2(const Tensor2Expression<A, Index<N1, I> , Index<N2, J> >& a) {
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for (int j = 0; j < N2; j++)
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T[j] = a(j);
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}
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/// @}
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/// @name Standard Interface
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/// @{
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/** dimension - TODO: is this right for anything other than 3x3? */
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size_t dim() const {return N1 * N2;}
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/// const element access
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const double & operator()(int i, int j) const {
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return T[j](i);
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}
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/// element access
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double & operator()(int i, int j) {
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return T[j](i);
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}
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/** convert to expression */
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template<char I, char J> Tensor2Expression<Tensor2, Index<N1, I> , Index<
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N2, J> > operator()(Index<N1, I> i, Index<N2, J> j) const {
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return Tensor2Expression<Tensor2, Index<N1, I> , Index<N2, J> > (*this);
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}
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/// @}
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};
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} // namespace tensors
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