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gh-120950: Fix overflow in math.log() with large int-like argument (GH-121011)

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Handling of arbitrary large int-like argument is now consistent with
handling arbitrary large int arguments.
This commit is contained in:
Serhiy Storchaka 2025-11-12 00:27:13 +02:00 • committed by GitHub
parent 9e7340cd3b
commit 4359706ac8
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3 changed files with 111 additions and 30 deletions
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59
Lib/test/test_math.py
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@ -189,6 +189,22 @@ def __init__(self, value):
def __index__(self):
return self.value
class IndexableFloatLike:
def __init__(self, float_value, index_value):
self.float_value = float_value
self.index_value = index_value
def __float__(self):
if isinstance(self.float_value, BaseException):
raise self.float_value
return self.float_value
def __index__(self):
if isinstance(self.index_value, BaseException):
raise self.index_value
return self.index_value
class BadDescr:
def __get__(self, obj, objtype=None):
raise ValueError
@ -1192,13 +1208,32 @@ def testLog(self):
self.ftest('log(10**40, 10**20)', math.log(10**40, 10**20), 2)
self.ftest('log(10**1000)', math.log(10**1000),
2302.5850929940457)
self.ftest('log(10**2000, 10**1000)', math.log(10**2000, 10**1000), 2)
self.ftest('log(MyIndexable(32), MyIndexable(2))',
math.log(MyIndexable(32), MyIndexable(2)), 5)
self.ftest('log(MyIndexable(10**1000))',
math.log(MyIndexable(10**1000)),
2302.5850929940457)
self.ftest('log(MyIndexable(10**2000), MyIndexable(10**1000))',
math.log(MyIndexable(10**2000), MyIndexable(10**1000)),
2)
self.assertRaises(ValueError, math.log, 0.0)
self.assertRaises(ValueError, math.log, 0)
self.assertRaises(ValueError, math.log, MyIndexable(0))
self.assertRaises(ValueError, math.log, -1.5)
self.assertRaises(ValueError, math.log, -1)
self.assertRaises(ValueError, math.log, MyIndexable(-1))
self.assertRaises(ValueError, math.log, -10**1000)
self.assertRaises(ValueError, math.log, MyIndexable(-10**1000))
self.assertRaises(ValueError, math.log, 10, -10)
self.assertRaises(ValueError, math.log, NINF)
self.assertEqual(math.log(INF), INF)
self.assertTrue(math.isnan(math.log(NAN)))
self.assertEqual(math.log(IndexableFloatLike(math.e, 10**1000)), 1.0)
self.assertAlmostEqual(math.log(IndexableFloatLike(OverflowError(), 10**1000)),
2302.5850929940457)
def testLog1p(self):
self.assertRaises(TypeError, math.log1p)
for n in [2, 2**90, 2**300]:
@ -1214,16 +1249,28 @@ def testLog2(self):
self.assertEqual(math.log2(1), 0.0)
self.assertEqual(math.log2(2), 1.0)
self.assertEqual(math.log2(4), 2.0)
self.assertEqual(math.log2(MyIndexable(4)), 2.0)
# Large integer values
self.assertEqual(math.log2(2**1023), 1023.0)
self.assertEqual(math.log2(2**1024), 1024.0)
self.assertEqual(math.log2(2**2000), 2000.0)
self.assertEqual(math.log2(MyIndexable(2**2000)), 2000.0)
self.assertRaises(ValueError, math.log2, 0.0)
self.assertRaises(ValueError, math.log2, 0)
self.assertRaises(ValueError, math.log2, MyIndexable(0))
self.assertRaises(ValueError, math.log2, -1.5)
self.assertRaises(ValueError, math.log2, -1)
self.assertRaises(ValueError, math.log2, MyIndexable(-1))
self.assertRaises(ValueError, math.log2, -2**2000)
self.assertRaises(ValueError, math.log2, MyIndexable(-2**2000))
self.assertRaises(ValueError, math.log2, NINF)
self.assertTrue(math.isnan(math.log2(NAN)))
self.assertEqual(math.log2(IndexableFloatLike(8.0, 2**2000)), 3.0)
self.assertEqual(math.log2(IndexableFloatLike(OverflowError(), 2**2000)), 2000.0)
@requires_IEEE_754
# log2() is not accurate enough on Mac OS X Tiger (10.4)
@support.requires_mac_ver(10, 5)
@ -1239,12 +1286,24 @@ def testLog10(self):
self.ftest('log10(1)', math.log10(1), 0)
self.ftest('log10(10)', math.log10(10), 1)
self.ftest('log10(10**1000)', math.log10(10**1000), 1000.0)
self.ftest('log10(MyIndexable(10))', math.log10(MyIndexable(10)), 1)
self.ftest('log10(MyIndexable(10**1000))',
math.log10(MyIndexable(10**1000)), 1000.0)
self.assertRaises(ValueError, math.log10, 0.0)
self.assertRaises(ValueError, math.log10, 0)
self.assertRaises(ValueError, math.log10, MyIndexable(0))
self.assertRaises(ValueError, math.log10, -1.5)
self.assertRaises(ValueError, math.log10, -1)
self.assertRaises(ValueError, math.log10, MyIndexable(-1))
self.assertRaises(ValueError, math.log10, -10**1000)
self.assertRaises(ValueError, math.log10, MyIndexable(-10**1000))
self.assertRaises(ValueError, math.log10, NINF)
self.assertEqual(math.log(INF), INF)
self.assertTrue(math.isnan(math.log10(NAN)))
self.assertEqual(math.log10(IndexableFloatLike(100.0, 10**1000)), 2.0)
self.assertEqual(math.log10(IndexableFloatLike(OverflowError(), 10**1000)), 1000.0)
@support.bigmemtest(2**32, memuse=0.2)
def test_log_huge_integer(self, size):
v = 1 << size