Message 135577 - Python tracker

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In-reply-to
Author	vstinner
Recipients	jcea, mark.dickinson, python-dev, rhettinger, vstinner
Date	2011年05月09日.12:10:12
SpamBayes Score	0.0014031121
Marked as misclassified	No
Message-id	<1304943013.84.0.527719124859.issue11888@psf.upfronthosting.co.za>

Content
Issue #11888: Use system log2() when available http://hg.python.org/cpython/rev/565f43f6bed4 "I expect the system libc to use more accurate functions than Python." You know what? Mac OS X log2 is less accurate than Python log2! A log2 test failed on "x86 Tiger 3.x": http://www.python.org/dev/buildbot/all/builders/x86%20Tiger%203.x/builds/2488 ====================================================================== FAIL: testLog2 (test.test_math.MathTests) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Users/db3l/buildarea/3.x.bolen-tiger/build/Lib/test/test_math.py", line 658, in testLog2 self.assertEqual(actual, expected) AssertionError: Lists differ: [-324.0, -323.0, -322.0, -321.... != [-324.0, -323.0, -322.0, -321.... First differing element 69: -254.99999999999997 -255.0 ---------------------------------------------------------------------- Should I revert my patch or should we test the system log2 in configure to check if it is as accurate or more accurate than Mark's algorithm?

Content

Issue #11888: Use system log2() when available
http://hg.python.org/cpython/rev/565f43f6bed4
"I expect the system libc to use more accurate functions than Python."
You know what? Mac OS X log2 is less accurate than Python log2! A log2 test failed on "x86 Tiger 3.x":
http://www.python.org/dev/buildbot/all/builders/x86%20Tiger%203.x/builds/2488
======================================================================
FAIL: testLog2 (test.test_math.MathTests)
----------------------------------------------------------------------
Traceback (most recent call last):
 File "/Users/db3l/buildarea/3.x.bolen-tiger/build/Lib/test/test_math.py", line 658, in testLog2
 self.assertEqual(actual, expected)
AssertionError: Lists differ: [-324.0, -323.0, -322.0, -321.... != [-324.0, -323.0, -322.0, -321....
First differing element 69:
-254.99999999999997
-255.0
----------------------------------------------------------------------
Should I revert my patch or should we test the system log2 in configure to check if it is as accurate or more accurate than Mark's algorithm?

History
Date	User	Action	Args
2011年05月09日 12:10:13	vstinner	set	recipients: + vstinner, rhettinger, jcea, mark.dickinson, python-dev
2011年05月09日 12:10:13	vstinner	set	messageid: <1304943013.84.0.527719124859.issue11888@psf.upfronthosting.co.za>
2011年05月09日 12:10:13	vstinner	link	issue11888 messages
2011年05月09日 12:10:12	vstinner	create

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