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Merged in JonasMu/eigen (pull request PR-329)

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Added an example for a contraction to a scalar value to README.md

Approved-by: Jonas Harsch <jonas.harsch@gmail.com>
This commit is contained in:
Benoit Steiner 2017-10-27 07:27:46 +00:00
commit 3949615176
1 changed files with 10 additions and 3 deletions
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unsupported/Eigen/CXX11/src/Tensor/README.md
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@ -1016,13 +1016,20 @@ multidimensional case.
a.setValues({{1, 2}, {4, 5}, {5, 6}});
// Compute the traditional matrix product
array<IndexPair<int>, 1> product_dims = { IndexPair(1, 0) };
Eigen::array<Eigen::IndexPair<int>, 1> product_dims = { Eigen::IndexPair(1, 0) };
Eigen::Tensor<int, 2> AB = a.contract(b, product_dims);
// Compute the product of the transpose of the matrices
array<IndexPair<int>, 1> transpose_product_dims = { IndexPair(0, 1) };
Eigen::array<Eigen::IndexPair<int>, 1> transpose_product_dims = { Eigen::IndexPair(0, 1) };
Eigen::Tensor<int, 2> AtBt = a.contract(b, transposed_product_dims);
// Contraction to scalar value using a ouble contraction
// First coordinate of both tensors are contracted as well as both second coordinates
Eigen::array<Eigen::IndexPair<int>, 2> double_contraction_product_dims = { Eigen::IndexPair<int>(0, 0), Eigen::IndexPair<int>(1, 1) };
Eigen::Tensor<int, 0> AdoubleontractedA = a.contract(a, double_contraction_product_dims);
// Extracting the scalar value of the tensor contraction for further usage
int value = AdoublecontractedA(0);
## Reduction Operations