[issue31630] math.tan has poor accuracy near pi/2 on OpenBSD

[Serhiy Storchaka]

New submission from Serhiy Storchaka <storchaka+cpython at gmail.com>:

test_math and test_cmath fail on OpenBSD 6.1.

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FAIL: test_testfile (test.test_math.MathTests)
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Traceback (most recent call last):
  File "/home/serhiy/py/cpython3.7/Lib/test/test_math.py", line 1349, in test_testfile
    '\n  '.join(failures))
AssertionError: Failures in test_testfile:
  tan0064: tan(1.5707963267948961): expected 1978937966095219.0, got 1978945885716843.0 (error = 7.92e+09 (31678486496 ulps); permitted error = 0 or 5 ulps)

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======================================================================
FAIL: test_specific_values (test.test_cmath.CMathTests)
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Traceback (most recent call last):
  File "/home/serhiy/py/cpython3.7/Lib/test/test_cmath.py", line 418, in test_specific_values
    msg=error_message)
  File "/home/serhiy/py/cpython3.7/Lib/test/test_cmath.py", line 149, in rAssertAlmostEqual
    '{!r} and {!r} are not sufficiently close'.format(a, b))
AssertionError: tan0064: tan(complex(1.5707963267948961, 0.0))
Expected: complex(1978937966095219.0, 0.0)
Received: complex(1978945885716843.0, 0.0)
Received value insufficiently close to expected value.

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Similar issue is issue27953.

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components: Extension Modules
messages: 303311
nosy: mark.dickinson, serhiy.storchaka
priority: normal
severity: normal
status: open
title: math.tan has poor accuracy near pi/2 on OpenBSD
type: behavior

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue31630>
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