Mirror
/
cpython
mirror of https://github.com/python/cpython
4
1
Fork 0
Code Issues Releases Wiki Activity

Merged revisions 71837-71838 via svnmerge from 

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r71837 | mark.dickinson | 2009-04-24 17:34:14 +0100 (Fri, 24 Apr 2009) | 4 lines

  Issue #5593: Use more robust test for double-rounding in test_fsum.
  While we're at it, use new unittest.skipUnless decorator to
  implement skipping for that test.
........
  r71838 | mark.dickinson | 2009-04-24 17:37:22 +0100 (Fri, 24 Apr 2009) | 2 lines

  Remove unnecessary double negative
........
This commit is contained in:
Mark Dickinson 2009-04-24 16:39:07 +00:00
parent d4d95f8eac
commit 5c56708f68
1 changed files with 9 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
Lib/test/test_math.py
View File

@ -13,6 +13,11 @@ NAN = float('nan')
INF = float('inf')
NINF = float('-inf')
# detect evidence of double-rounding: fsum is not always correctly
# rounded on machines that suffer from double rounding.
x, y = 1e16, 2.9999 # use temporary values to defeat peephole optimizer
HAVE_DOUBLE_ROUNDING = (x + y == 1e16 + 4)
# locate file with test values
if __name__ == '__main__':
file = sys.argv[0]
@ -359,6 +364,10 @@ class MathTests(unittest.TestCase):
self.assertEquals(math.frexp(NINF)[0], NINF)
self.assert_(math.isnan(math.frexp(NAN)[0]))
@unittest.skipUnless(float.__getformat__("double").startswith("IEEE"),
"test requires IEEE 754 doubles")
@unittest.skipIf(HAVE_DOUBLE_ROUNDING,
"fsum is not exact on machines with double rounding")
def testFsum(self):
# math.fsum relies on exact rounding for correct operation.
# There's a known problem with IA32 floating-point that causes
@ -368,14 +377,6 @@ class MathTests(unittest.TestCase):
# problem described in issue #2937, we simply skip the whole
# test.
if not float.__getformat__("double").startswith("IEEE"):
return
# on IEEE 754 compliant machines, both of the expressions
# below should round to 10000000000000002.0.
if 1e16+2.0 != 1e16+2.9999:
return
# Python version of math.fsum, for comparison. Uses a
# different algorithm based on frexp, ldexp and integer
# arithmetic.