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# This file is part of Hypothesis, which may be found at
# https://github.com/HypothesisWorks/hypothesis/
#
# Copyright the Hypothesis Authors.
# Individual contributors are listed in AUTHORS.rst and the git log.
#
# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/.
import math
import sys
from sys import float_info
import pytest
from hypothesis import assume, given
from hypothesis.internal.cathetus import cathetus
from hypothesis.strategies import floats
def test_cathetus_subnormal_underflow():
u = sys.float_info.min * sys.float_info.epsilon
h = 5 * u
a = 4 * u
assert cathetus(h, a) == 3 * u
def test_cathetus_simple_underflow():
a = sys.float_info.min
h = a * math.sqrt(2)
b = cathetus(h, a)
assert b > 0, f"expecting positive cathetus({h:g}, {a:g}), got {b:g}"
def test_cathetus_huge_no_overflow():
h = sys.float_info.max
a = h / math.sqrt(2)
b = cathetus(h, a)
assert math.isfinite(b), f"expecting finite cathetus({h:g}, {a:g}), got {b:g}"
def test_cathetus_large_no_overflow():
h = sys.float_info.max / 3
a = h / math.sqrt(2)
b = cathetus(h, a)
assert math.isfinite(b), f"expecting finite cathetus({h:g}, {a:g}), got {b:g}"
@pytest.mark.parametrize(
"h,a",
[
# NaN hypot
(math.nan, 3),
(math.nan, 0),
(math.nan, math.inf),
(math.nan, math.nan),
# Infeasible
(2, 3),
(2, -3),
(2, math.inf),
(2, math.nan),
# Surprisingly consistent with c99 hypot()
(math.inf, math.inf),
],
)
def test_cathetus_nan(h, a):
assert math.isnan(cathetus(h, a))
@pytest.mark.parametrize(
"h,a", [(math.inf, 3), (math.inf, -3), (math.inf, 0), (math.inf, math.nan)]
)
def test_cathetus_infinite(h, a):
assert math.isinf(cathetus(h, a))
@pytest.mark.parametrize(
"h,a,b", [(-5, 4, 3), (5, -4, 3), (-5, -4, 3), (0, 0, 0), (1, 0, 1)]
)
def test_cathetus_signs(h, a, b):
assert abs(cathetus(h, a) - b) <= abs(b) * float_info.epsilon
@given(
h=floats(0) | floats(min_value=1e308, allow_infinity=False),
a=floats(0, allow_infinity=False)
| floats(min_value=0, max_value=1e250, allow_infinity=False),
)
def test_cathetus_always_leq_hypot(h, a):
assume(h >= a)
b = cathetus(h, a)
assert 0 <= b <= h
@pytest.mark.parametrize(
"a,b,h",
[
(3, 4, 5),
(5, 12, 13),
(8, 15, 17),
(7, 24, 25),
(20, 21, 29),
(12, 35, 37),
(9, 40, 41),
(28, 45, 53),
(11, 60, 61),
(16, 63, 65),
(33, 56, 65),
(48, 55, 73),
(13, 84, 85),
(36, 77, 85),
(39, 80, 89),
(65, 72, 97),
(20, 99, 101),
(60, 91, 109),
(15, 112, 113),
(44, 117, 125),
(88, 105, 137),
(17, 144, 145),
(24, 143, 145),
(51, 140, 149),
(85, 132, 157),
(119, 120, 169),
(52, 165, 173),
(19, 180, 181),
(57, 176, 185),
(104, 153, 185),
(95, 168, 193),
(28, 195, 197),
(84, 187, 205),
(133, 156, 205),
(21, 220, 221),
(140, 171, 221),
(60, 221, 229),
(105, 208, 233),
(120, 209, 241),
(32, 255, 257),
(23, 264, 265),
(96, 247, 265),
(69, 260, 269),
(115, 252, 277),
(160, 231, 281),
(161, 240, 289),
(68, 285, 293),
],
)
def test_pythagorean_triples(a, b, h):
assert abs(math.hypot(a, b) - h) <= abs(h) * float_info.epsilon
assert abs(cathetus(h, a) - b) <= abs(b) * float_info.epsilon
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