cpython/Lib/test/test_math_property.py
Matthias Görgens 6e39fa1955
gh-94906: Support multiple steps in math.nextafter (#103881)
This PR updates `math.nextafter` to add a new `steps` argument. The behaviour is as though `math.nextafter` had been called `steps` times in succession.

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Co-authored-by: Mark Dickinson <mdickinson@enthought.com>
2023-05-19 21:03:49 +01:00

42 lines
1.2 KiB
Python

import functools
import unittest
from math import isnan, nextafter
from test.support import requires_IEEE_754
from test.support.hypothesis_helper import hypothesis
floats = hypothesis.strategies.floats
integers = hypothesis.strategies.integers
def assert_equal_float(x, y):
assert isnan(x) and isnan(y) or x == y
def via_reduce(x, y, steps):
return functools.reduce(nextafter, [y] * steps, x)
class NextafterTests(unittest.TestCase):
@requires_IEEE_754
@hypothesis.given(
x=floats(),
y=floats(),
steps=integers(min_value=0, max_value=2**16))
def test_count(self, x, y, steps):
assert_equal_float(via_reduce(x, y, steps),
nextafter(x, y, steps=steps))
@requires_IEEE_754
@hypothesis.given(
x=floats(),
y=floats(),
a=integers(min_value=0),
b=integers(min_value=0))
def test_addition_commutes(self, x, y, a, b):
first = nextafter(x, y, steps=a)
second = nextafter(first, y, steps=b)
combined = nextafter(x, y, steps=a+b)
hypothesis.note(f"{first} -> {second} == {combined}")
assert_equal_float(second, combined)