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gh-117999: fixed small nonnegative integer powers of complex numbers #118000

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gh-117999: fixed small nonnegative integer powers of complex numbers #118000

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70d21c7
gh-117999: fixed small nonnegative integer powers of complex numbers
skirpichev Apr 17, 2024
8e0c482
Polishing of c_powu(): exclude unreachible cases and magic numbers
skirpichev May 29, 2024
6fb1d12
Use _Py_c_pow() to test implementation
skirpichev May 30, 2024
87c420a
Merge branch 'main' into fix-c_powi-117999
skirpichev May 31, 2024
389441d
Apply suggestions from code review
skirpichev Aug 19, 2024
9f24ad1
Apply suggestions from code review
skirpichev Aug 19, 2024
807bcc6
Address review: subTest and asserts
skirpichev Aug 19, 2024
b3ec9c6
Merge branch 'main' into fix-c_powi-117999
skirpichev Sep 17, 2025
8cc2a2b
rename news
skirpichev Sep 17, 2025
9e9b454
take tests from #124243
skirpichev Sep 17, 2025
7f25e09
Use new _Py_rc_quot()
skirpichev Sep 17, 2025
99c7be1
run _Py_ADJUST_ERANGE2 only for finite input
skirpichev Sep 17, 2025
a86abc1
inline c_1
skirpichev Sep 17, 2025
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61 changes: 61 additions & 0 deletions Lib/test/test_complex.py
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Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,10 @@ def assertClose(self, x, y, eps=1e-9):
self.assertCloseAbs(x.real, y.real, eps)
self.assertCloseAbs(x.imag, y.imag, eps)

def assertSameSign(self, x, y):
if copysign(1., x) != copysign(1., y):
self.fail(f'{x!r} and {y!r} have different signs')

def check_div(self, x, y):
"""Compute complex z=x*y, and check that z/x==y and z/y==x."""
z = x * y
Expand Down Expand Up @@ -447,6 +451,63 @@ def test_pow_with_small_integer_exponents(self):
self.assertEqual(str(float_pow), str(int_pow))
self.assertEqual(str(complex_pow), str(int_pow))

# Check that complex numbers with special components
# are correctly handled.
values = [complex(x, y)
for x in [5, -5, +0.0, -0.0, INF, -INF, NAN]
for y in [12, -12, +0.0, -0.0, INF, -INF, NAN]]
for c in values:
with self.subTest(value=c):
self.assertComplexesAreIdentical(c**0, complex(1, +0.0))
self.assertComplexesAreIdentical(c**1, c)
self.assertComplexesAreIdentical(c**2, c*c)
self.assertComplexesAreIdentical(c**3, c*(c*c))
self.assertComplexesAreIdentical(c**3, (c*c)*c)
if not c:
continue
for n in range(1, 9):
with self.subTest(exponent=-n):
self.assertComplexesAreIdentical(c**-n, 1/(c**n))

# Special cases for complex division.
for x in [+2, -2]:
for y in [+0.0, -0.0]:
c = complex(x, y)
with self.subTest(value=c):
self.assertComplexesAreIdentical(c**-1, complex(1/x, -y))