https://github.com/python/cpython/commit/5f7d7096129e055dc34838dfc2aee2190c635006 commit: 5f7d7096129e055dc34838dfc2aee2190c635006 branch: main author: Serhiy Storchaka <[email protected]> committer: serhiy-storchaka <[email protected]> date: 2026-09-04T08:10:28Z summary:
gh-156886: Fix spurious ZeroDivisionError for complex powers (GH-156887) cos() and sin() of an infinite phase set errno to EDOM, which complex_pow() reported as a zero base. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]> files: A Misc/NEWS.d/next/Core_and_Builtins/2026-09-03-12-40-00.gh-issue-156886.Kx7mQt.rst M Lib/test/test_complex.py M Objects/complexobject.c diff --git a/Lib/test/test_complex.py b/Lib/test/test_complex.py index 4cc9eea1f27214..3d02bb6ec2389b 100644 --- a/Lib/test/test_complex.py +++ b/Lib/test/test_complex.py @@ -366,6 +366,16 @@ def test_pow(self): self.assertRaises(TypeError, pow, None, 1j) self.assertAlmostEqual(pow(1j, 0.5), 0.7071067811865476+0.7071067811865475j) + # gh-156886: an infinite phase is not a zero base. + for base, exp in [(complex(INF), 1j), + (complex(INF, 1), 1j), + (1e300, 1e308j), + (complex(2), complex(0, INF))]: + with self.subTest(base=base, exponent=exp): + r = base ** exp + self.assertTrue(isnan(r.real)) + self.assertTrue(isnan(r.imag)) + a = 3.33+4.43j self.assertEqual(a ** 0j, 1) self.assertEqual(a ** 0.+0.j, 1) diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-09-03-12-40-00.gh-issue-156886.Kx7mQt.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-03-12-40-00.gh-issue-156886.Kx7mQt.rst new file mode 100644 index 00000000000000..69fbc33992100e --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-03-12-40-00.gh-issue-156886.Kx7mQt.rst @@ -0,0 +1,3 @@ +Fix :exc:`ZeroDivisionError` spuriously raised for a complex power +with a non-zero base when the phase of the result is infinite, +e.g. ``1e300**1e308j`` or ``complex('inf')**1j``. diff --git a/Objects/complexobject.c b/Objects/complexobject.c index 5f7acdeb7cfd8d..9328baf013c972 100644 --- a/Objects/complexobject.c +++ b/Objects/complexobject.c @@ -331,6 +331,9 @@ _Py_c_pow(Py_complex a, Py_complex b) r.real = len*cos(phase); r.imag = len*sin(phase); + /* Don't rely on errno set by the math functions above, for + example cos() and sin() set EDOM for an infinite phase. */ + errno = 0; if (isfinite(a.real) && isfinite(a.imag) && isfinite(b.real) && isfinite(b.imag)) { _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
