CODEWITHSUNDEEP
c++eigen
kloop
kloop

Reputation: 4731

Why the following Eigen example won't compile?

I am trying to compile this MWE, but getting lots of errors:

#include <eigen/Eigen/Core>
#include <eigen/unsupported/Eigen/CXX11/Tensor>
#include <array>

using namespace Eigen;

int main()
{
// Create 2 matrices using tensors of rank 2
Eigen::Tensor<int, 2> a(2, 3);
a.setValues({{1, 2, 3}, {6, 5, 4}});
Eigen::Tensor<int, 2> b(3, 2);
a.setValues({{1, 2}, {4, 5}, {5, 6}});

// Compute the traditional matrix product
array<IndexPair<int>, 1> product_dims = { IndexPair<int>(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<int>(0, 1) };
Eigen::Tensor<int, 2> AtBt = a.contract(b, transpose_product_dims);
}

This is actually from an example for Eigen tensors:

https://bitbucket.org/eigen/eigen/src/default/unsupported/Eigen/CXX11/src/Tensor/README.md?fileviewer=file-view-default

about contraction but I think it has some errors and wasn't compiled properly, which I tried to fix.

errors:

1.cc:11:3: error: no member named 'setValues' in 'Eigen::Tensor<int, 2, 0, long>'
a.setValues({{1, 2, 3}, {6, 5, 4}});
~ ^
1.cc:11:13: error: expected expression
a.setValues({{1, 2, 3}, {6, 5, 4}});
            ^
1.cc:13:3: error: no member named 'setValues' in 'Eigen::Tensor<int, 2, 0, long>'
a.setValues({{1, 2}, {4, 5}, {5, 6}});
~ ^
1.cc:13:13: error: expected expression
a.setValues({{1, 2}, {4, 5}, {5, 6}});
            ^
1.cc:16:26: error: non-aggregate type 'array<IndexPair<int>, 1>' cannot be initialized with an initializer list
array<IndexPair<int>, 1> product_dims = { IndexPair<int>(1, 0) };
                         ^              ~~~~~~~~~~~~~~~~~~~~~~~~
1.cc:20:26: error: non-aggregate type 'array<IndexPair<int>, 1>' cannot be initialized with an initializer list
array<IndexPair<int>, 1> transpose_product_dims = { IndexPair<int>(0, 1) };
                         ^                        ~~~~~~~~~~~~~~~~~~~~~~~~
6 errors generated.

Upvotes: 1

Views: 1724

Answers (1)

ggael
ggael

Reputation: 29255

This example requires c++11, so you need to enable it on your compiler, for instance using -std=c++11 with gcc prior to gcc 6 or clang.

Upvotes: 1

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