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Issue with calculating contraction #14

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rj-calvin opened this issue Jul 8, 2019 · 1 comment · May be fixed by #15
Open

Issue with calculating contraction #14

rj-calvin opened this issue Jul 8, 2019 · 1 comment · May be fixed by #15

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@rj-calvin
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rj-calvin commented Jul 8, 2019 •
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For some reason the API has it that
equation

Currently, the left hand side yields the correct value while the right hand side sums the diagonal components of the array representing the tensor literally.

However this is only an issue with contractions on a single tensor (not a product of tensors), and when the contraction yields a scalar. Meaning that the calculation of the Ricci tensor is fine, but the Ricci scalar is not.
@rj-calvin
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rj-calvin commented Jul 8, 2019 •
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This is an issue with https://github.com/sympy/sympy.

The ~sympy.tensor.tensor.Tensor._extract_data method contracts indices without applying the metric to the arrays in the replacement_dict argument.

@rj-calvin rj-calvin linked a pull request Jul 8, 2019 that will close this issue
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Ricci scalar fix
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@rj-calvin