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gh-153144: Avoid checking errno for atan2 #153148

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503fd4a
gh-153144: Avoid checking `errno` for `atan2`
hpkfft Jul 5, 2026
c9c51ad
gh-153144: Added NEWS entry
hpkfft Jul 20, 2026
287e6ee
gh-153144: Modify comments as requested in review
hpkfft Jul 21, 2026
cbe759a
Merge branch 'main' into atan2
hpkfft Aug 1, 2026
91257f2
Merge branch 'main' into atan2
hpkfft Aug 13, 2026
25ec8e2
Add comments as requested in review
hpkfft Aug 14, 2026
43f7398
Revert gh-146402 and update NEWS entry
hpkfft Aug 14, 2026
5b6d005
Merge branch 'main' into atan2
skirpichev Aug 30, 2026
ead2720
Make NEWS entry a little shorter.
hpkfft Aug 30, 2026
d546e81
The copysign function does not need to check errno.
hpkfft Aug 30, 2026
f4ed052
Merge branch 'main' into atan2
hpkfft Sep 8, 2026
82448e1
Add cmath tests and update NEWS entry
hpkfft Sep 8, 2026
288fb8b
Merge branch 'main' into atan2
hpkfft Sep 18, 2026
be0ed87
Expand comments to explain why we ignore errno
hpkfft Sep 18, 2026
b991892
Merge branch 'main' into atan2
hpkfft Sep 18, 2026
72842e1
Merge branch 'main' into atan2
hpkfft Oct 1, 2026
11c56c4
Merge branch 'main' into atan2
hpkfft Oct 3, 2026
6a92490
Change as requested in review
hpkfft Oct 3, 2026
6a48f02
Merge branch 'main' into atan2
hpkfft Oct 4, 2026
8594452
Add tests for math.atan2() and update NEWS
hpkfft Oct 4, 2026
527afd1
Remove decorative `*` from comment in cmathmodule
hpkfft Oct 4, 2026
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The copysign function does not need to check errno.
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@hpkfft
hpkfft committed Aug 30, 2026
commit d546e8120b94782e22dbf604841c5e584c46a85e
4 changes: 2 additions & 2 deletions Modules/mathmodule.c
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Expand Up @@ -1017,7 +1017,7 @@ math_1a(PyObject *arg, double (*func) (double), const char *err_msg)
The last rule is used to catch overflow on platforms which follow
C89 but for which HUGE_VAL is not an infinity.

For most two-argument functions (copysign, fmod, hypot)
For most two-argument functions (fmod, hypot)

@skirpichev skirpichev Oct 4, 2026

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Actually, the only remaining math_2()-type function is remainder()...

@hpkfft hpkfft Oct 4, 2026

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I think (fmod, hypot) in the comment above refers to the C math library functions.
Unless I've missed it, Python does not use the C math library function double remainder(double, double), so I don't think we should add it to this comment.

@skirpichev skirpichev Oct 5, 2026 •
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I think (fmod, hypot) in the comment above refers to the C math library functions.

I don't think so. Before 53876d9, both fmod and hypot were using FUNC2 macro.

Python does not use the C math library function double remainder(double, double)

Yes, but m_remainder (name in style m_log and co, suggesting a workarounded libm's function) is just an implementation of Annex F remainder.

Perhaps, nowadays we could replace this function by standard library call: at least this works well for me locally. See previous attempt of removing legacy stuff: #101679

Edit: FYI, #158826.

@hpkfft hpkfft Oct 5, 2026

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Interesting. But it seems sufficiently unrelated as to allow this PR to be merged without further tweaks to the comments.

these rules are enough to ensure that Python's functions behave as
specified in 'Annex F' of the C99 standard, with the 'invalid' and
'divide-by-zero' floating-point exceptions mapping to Python's
Expand Down Expand Up @@ -1206,7 +1206,7 @@ math_ceil(PyObject *module, PyObject *number)
return PyLong_FromDouble(ceil(x));
}

FUNC2(copysign, copysign,
FUNC2NE(copysign, copysign,
Comment thread
picnixz marked this conversation as resolved.
"copysign($module, x, y, /)\n--\n\n"
"Return a float with the magnitude (absolute value) of x but the sign of y.\n\n"
"On platforms that support signed zeros, copysign(1.0, -0.0)\n"
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