gh-144173: fix flaky test_complex.test_truediv()#144355
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vstinner merged 1 commit intopython:mainfrom Mar 10, 2026
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Previously, component-wise relative error bound was tested. However, such bound can't exist already for complex multiplication as one can be used to perform subtraction of floating-point numbers, e.g. x and y for z0=1+1j and z1=x+yj. ```pycon >>> x, y = 1e-9+1j, 1+1j >>> a = x*y*y.conjugate()/2;a (1.0000000272292198e-09+1j) >>> b = x*(y*y.conjugate()/2);b (1e-09+1j) >>> b == x True >>> (a.real-b.real)/math.ulp(b.real) 131672427.0 ```
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CC @tim-one |
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CC @encukou |
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This could be backported. Though, chances to hit this issue looks really low. |
vstinner
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needs backport to 3.13
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Thanks @skirpichev for the PR, and @vstinner for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14. |
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Previously, component-wise relative error bound was tested. However, such bound can't exist already for complex multiplication as one can be used to perform subtraction of floating-point numbers, e.g. x and y for z0=1+1j and z1=x+yj. ```pycon >>> x, y = 1e-9+1j, 1+1j >>> a = x*y*y.conjugate()/2;a (1.0000000272292198e-09+1j) >>> b = x*(y*y.conjugate()/2);b (1e-09+1j) >>> b == x True >>> (a.real-b.real)/math.ulp(b.real) 131672427.0 ``` (cherry picked from commit c4333a1) Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
miss-islington
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Mar 10, 2026
Previously, component-wise relative error bound was tested. However, such bound can't exist already for complex multiplication as one can be used to perform subtraction of floating-point numbers, e.g. x and y for z0=1+1j and z1=x+yj. ```pycon >>> x, y = 1e-9+1j, 1+1j >>> a = x*y*y.conjugate()/2;a (1.0000000272292198e-09+1j) >>> b = x*(y*y.conjugate()/2);b (1e-09+1j) >>> b == x True >>> (a.real-b.real)/math.ulp(b.real) 131672427.0 ``` (cherry picked from commit c4333a1) Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
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GH-145766 is a backport of this pull request to the 3.14 branch. |
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GH-145767 is a backport of this pull request to the 3.13 branch. |
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Merged. Thanks for the fix. |
vstinner
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…145767) gh-144173: fix flaky test_complex.test_truediv() (GH-144355) Previously, component-wise relative error bound was tested. However, such bound can't exist already for complex multiplication as one can be used to perform subtraction of floating-point numbers, e.g. x and y for z0=1+1j and z1=x+yj. ```pycon >>> x, y = 1e-9+1j, 1+1j >>> a = x*y*y.conjugate()/2;a (1.0000000272292198e-09+1j) >>> b = x*(y*y.conjugate()/2);b (1e-09+1j) >>> b == x True >>> (a.real-b.real)/math.ulp(b.real) 131672427.0 ``` (cherry picked from commit c4333a1) Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
vstinner
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Mar 10, 2026
…145766) gh-144173: fix flaky test_complex.test_truediv() (GH-144355) Previously, component-wise relative error bound was tested. However, such bound can't exist already for complex multiplication as one can be used to perform subtraction of floating-point numbers, e.g. x and y for z0=1+1j and z1=x+yj. ```pycon >>> x, y = 1e-9+1j, 1+1j >>> a = x*y*y.conjugate()/2;a (1.0000000272292198e-09+1j) >>> b = x*(y*y.conjugate()/2);b (1e-09+1j) >>> b == x True >>> (a.real-b.real)/math.ulp(b.real) 131672427.0 ``` (cherry picked from commit c4333a1) Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
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Previously, component-wise relative error bound was tested. However, such bound can't exist already for complex multiplication as one can be used to perform subtraction of floating-point numbers, e.g. x and y for z0=1+1j and z1=x+yj.