fix: complex dot_product formulation #1017
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Pull Request Overview
This PR fixes the complex dot product formulation in the stdlib intrinsics implementation to ensure compliance with the mathematical standard. The fix addresses issue #1016 by correcting the conjugation logic in complex number multiplication.
- Modifies the complex dot product implementation to conjugate the first vector instead of the second
- Updates both the standard and Kahan summation variants of the dot product functions
- Adds comprehensive test coverage to verify conformance with the compiler intrinsic behavior
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| src/stdlib_intrinsics_dot_product.fypp | Corrects conjugation order in complex dot product calculations for both standard and Kahan variants |
| test/intrinsics/test_intrinsics.fypp | Adds test case comparing stdlib implementations against compiler intrinsic to ensure standard conformance |
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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* fix complex dot_product formulation * smaller array and wider tolerance * Update test/intrinsics/test_intrinsics.fypp Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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* fix complex dot_product formulation * smaller array and wider tolerance * Update test/intrinsics/test_intrinsics.fypp Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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* fix complex dot_product formulation * smaller array and wider tolerance * Update test/intrinsics/test_intrinsics.fypp Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
perazz
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Jul 23, 2025
| block ! test for https://github.com/fortran-lang/stdlib/issues/1016 | ||
| ${t}$ :: x(128), y(128) | ||
| real(${k}$) :: z(128,2) | ||
| real(${k}$), parameter :: tolerance = epsilon(1._${k}$)*100000 |
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For a 32-bit precision dot product, this error is ~0.01, which seems a bit large? I believe using sqrt(epsilon(0.0_${k}$)) would be a more established error threshold in numerical analysis. LGTM otherwise.
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addresses #1016
cc: @loiseaujc