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gh-122637: fix tanh(±0+infj) and tanh(±0+nanj) to return ±0+nanj #122638

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merged 1 commit into from
Aug 4, 2024

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skirpichev
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@skirpichev skirpichev commented Aug 3, 2024

As per C11 DR#471, ctanh (0 + i NaN) and ctanh (0 + i Inf) should return 0 + i NaN (with "invalid" exception in the second case). This has corresponding implications for ctan(z), as its errors and special cases are handled as if the operation is implemented by -i*ctanh(i*z). This patch fixes cmath's code to do same.

Glibs patch: https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=d15e83c5f5231d971472b5ffc9219d54056ca0f1

As per C11 DR#471, ctanh (0 + i NaN) and ctanh (0 + i Inf) should return
0 + i NaN (with "invalid" exception in the second case).  This has
corresponding implications for ctan(z), as its errors and special cases
are handled as if the operation is implemented by -i*ctanh(i*z).
This patch fixes cmath's code to do same.

Glibs patch: https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=d15e83c5f5231d971472b5ffc9219d54056ca0f1
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LGTM. Thank you!

@mdickinson mdickinson merged commit e6fad7a into python:main Aug 4, 2024
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@skirpichev skirpichev deleted the fix-cmath-tanh-values-122637 branch August 4, 2024 09:26
brandtbucher pushed a commit to brandtbucher/cpython that referenced this pull request Aug 7, 2024
python#122638)

As per C11 DR#471, ctanh (0 + i NaN) and ctanh (0 + i Inf) should return
0 + i NaN (with "invalid" exception in the second case).  This has
corresponding implications for ctan(z), as its errors and special cases
are handled as if the operation is implemented by -i*ctanh(i*z).
This patch fixes cmath's code to do same.

Glibs patch: https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=d15e83c5f5231d971472b5ffc9219d54056ca0f1
blhsing pushed a commit to blhsing/cpython that referenced this pull request Aug 22, 2024
python#122638)

As per C11 DR#471, ctanh (0 + i NaN) and ctanh (0 + i Inf) should return
0 + i NaN (with "invalid" exception in the second case).  This has
corresponding implications for ctan(z), as its errors and special cases
are handled as if the operation is implemented by -i*ctanh(i*z).
This patch fixes cmath's code to do same.

Glibs patch: https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=d15e83c5f5231d971472b5ffc9219d54056ca0f1
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2 participants