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Merged
merged 13 commits into from
Jan 23, 2025
Merged

Compute acos with less cancellation near x=1 #217

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075521e
a new failing test case
AldenMB Feb 13, 2023
05c3fd3
test case finder
AldenMB Feb 13, 2023
4c52aec
additional falsifyer
AldenMB Feb 13, 2023
0f36747
parametrize tests
AldenMB Feb 13, 2023
727eae8
check more cases
AldenMB Feb 13, 2023
2498123
test acosh
AldenMB Feb 13, 2023
0316809
remove extranous zero
AldenMB Feb 13, 2023
e634266
remove extraneous parameter
AldenMB Feb 13, 2023
2b1298c
use a method less prone to cancellation near x=1
AldenMB Feb 13, 2023
b3142b4
new falisifying test for sine
AldenMB Feb 13, 2023
6490629
search for more exampoles
AldenMB Feb 13, 2023
780480c
additional cosine test showing cancellation
AldenMB Feb 13, 2023
d130921
additional case showing loss of significance near x=1
AldenMB Feb 13, 2023
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parametrize tests
  • Loading branch information
@AldenMB
AldenMB committed Feb 13, 2023
commit 0f36747c05c15f734e86f920a099ffbc0fa8b5a9
152 changes: 55 additions & 97 deletions test/hypothesis/error_hunt.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,8 +5,10 @@
from hypothesis import given, settings
from hypothesis.strategies import decimals, integers, tuples
from mpmath import mp
import pytest

mp.prec = 500
getcontext().prec = 14

node = subprocess.Popen(
["node", "evaluate.mjs"], stdout=subprocess.PIPE, stdin=subprocess.PIPE
Expand All @@ -20,106 +22,62 @@ def get_decimal(func: str, args: list, config: dict):
return Decimal(node.stdout.readline().strip().decode())


def to_precision(x, precision=14):
getcontext().prec = precision
return Decimal(str(x)) * Decimal("1.0")


decimal_fixed_precision = tuples(
decimals(
allow_nan=False, allow_infinity=False, min_value=-1, max_value=1, places=14
),
integers(min_value=-99, max_value=99),
).map(lambda tup: tup[0] * Decimal(10) ** tup[1])

decimal_positive = tuples(
decimals(
allow_nan=False, allow_infinity=False, min_value=1e-13, max_value=1, places=14
),
integers(min_value=-99, max_value=99),
).map(lambda tup: tup[0] * Decimal(10) ** tup[1])


@given(decimal_fixed_precision)
@settings(max_examples=100)
def test_tangent(x):
y = to_precision(mp.tan(x))
z = get_decimal("tan", [str(x)], {"precision": 14})
assert y == z


@given(decimal_fixed_precision)
@settings(max_examples=100)
def test_cosine(x):
y = to_precision(mp.cos(x))
z = get_decimal("cos", [str(x)], {"precision": 14})
def assert_matches(x, mpfunc, jsfunc=None):
if jsfunc is None:
jsfunc = mpfunc
y = Decimal(str(getattr(mp, mpfunc)(x))) * Decimal("1.0")
z = get_decimal(jsfunc, [str(x)], {"precision": 14})
assert y == z


@given(decimal_fixed_precision)
@settings(max_examples=100)
def test_sine(x):
y = to_precision(mp.sin(x))
z = get_decimal("sin", [str(x)], {"precision": 14})
assert y == z


@given(decimal_positive)
@settings(max_examples=100)
def test_log(x):
y = to_precision(mp.log10(x))
z = get_decimal("log", [str(x)], {"precision": 14})
assert y == z


inverse_trig_strat = decimals(
allow_nan=False, allow_infinity=False, min_value=-1, max_value=1, places=14
@pytest.mark.parametrize("fn", "sin cos tan atan".split())
@given(
x=tuples(
decimals(
allow_nan=False, allow_infinity=False, min_value=-1, max_value=1, places=14
),
integers(min_value=-99, max_value=99),
).map(lambda tup: tup[0] * Decimal(10) ** tup[1])
)
def test_matches(x, fn):
assert_matches(x, fn)


@pytest.mark.parametrize("fn", "ln log10".split())
@given(
x=tuples(
decimals(
allow_nan=False,
allow_infinity=False,
min_value=1e-13,
max_value=1,
places=14,
),
integers(min_value=-99, max_value=99),
).map(lambda tup: tup[0] * Decimal(10) ** tup[1])
)
def test_positive_domain(x, fn):
assert_matches(x, fn)


@given(inverse_trig_strat)
@settings(max_examples=100)
def test_acos(x):
y = to_precision(mp.acos(x))
z = get_decimal("acos", [str(x)], {"precision": 14})
assert y == z


@given(inverse_trig_strat)
@settings(max_examples=100)
def test_asin(x):
y = to_precision(mp.asin(x))
z = get_decimal("asin", [str(x)], {"precision": 14})
assert y == z


@given(decimal_fixed_precision)
@settings(max_examples=100)
def test_atan(x):
y = to_precision(mp.atan(x))
z = get_decimal("atan", [str(x)], {"precision": 14})
assert y == z


@given(decimal_fixed_precision)
@settings(max_examples=10)
def test_cosh(x):
y = to_precision(mp.cosh(x))
z = get_decimal("cosh", [str(x)], {"precision": 14})
assert y == z


@given(decimal_fixed_precision)
@settings(max_examples=4)
def test_sinh(x):
y = to_precision(mp.sinh(x))
z = get_decimal("sinh", [str(x)], {"precision": 14})
assert y == z


@given(decimal_fixed_precision)
@settings(max_examples=4)
def test_tanh(x):
y = to_precision(mp.tanh(x))
z = get_decimal("tanh", [str(x)], {"precision": 14})
assert y == z
@pytest.mark.parametrize("fn", "asin acos".split())
@given(
x=decimals(
allow_nan=False, allow_infinity=False, min_value=-1, max_value=1, places=14
)
)
def test_inverse_trig(x, fn):
assert_matches(x, fn)


@pytest.mark.parametrize("fn", "sinh cosh tanh".split())
@given(
x=tuples(
decimals(
allow_nan=False, allow_infinity=False, min_value=-1, max_value=1, places=14
),
integers(min_value=-99, max_value=3),
).map(lambda tup: tup[0] * Decimal(10) ** tup[1])
)
def test_small_domain(x, fn):
assert_matches(x, fn)