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Merged revisions 82646,82649-82650 via svnmerge from 

svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r82646 | mark.dickinson | 2010-07-08 18:23:40 +0100 (Thu, 08 Jul 2010) | 1 line

  In test_decimal, convert heuristic for skipping tests into an explicit skiplist.
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  r82649 | mark.dickinson | 2010-07-08 20:03:34 +0100 (Thu, 08 Jul 2010) | 1 line

  Fix a performance issue in Decimal.pow.  Thanks Stefan Krah for finding this.
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  r82650 | mark.dickinson | 2010-07-08 20:09:16 +0100 (Thu, 08 Jul 2010) | 1 line

  Fix misplaced exactness check that was causing unnecessary work in Decimal.__pow__.
........
This commit is contained in:
Mark Dickinson 2010-07-08 19:21:59 +00:00
parent 1a1ea285f6
commit 0390f504ac
4 changed files with 64 additions and 50 deletions
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15
Lib/decimal.py
View File

@ -2044,12 +2044,14 @@ class Decimal(object):
# case where xc == 1: result is 10**(xe*y), with xe*y
# required to be an integer
if xc == 1:
if ye >= 0:
exponent = xe*yc*10**ye
else:
exponent, remainder = divmod(xe*yc, 10**-ye)
if remainder:
xe *= yc
# result is now 10**(xe * 10**ye); xe * 10**ye must be integral
while xe % 10 == 0:
xe //= 10
ye += 1
if ye < 0:
return None
exponent = xe * 10**ye
if y.sign == 1:
exponent = -exponent
# if other is a nonnegative integer, use ideal exponent
@ -2322,7 +2324,8 @@ class Decimal(object):
# try for an exact result with precision +1
if ans is None:
ans = self._power_exact(other, context.prec + 1)
if ans is not None and result_sign == 1:
if ans is not None:
if result_sign == 1:
ans = _dec_from_triple(1, ans._int, ans._exp)
exact = True

13
Lib/test/decimaltestdata/extra.decTest
View File

@ -213,7 +213,20 @@ extr1658 shift 1234567 3 -> 7000
extr1659 shift 1234567 4 -> 0
extr1660 shift 1234567 5 -> NaN Invalid_operation
-- Cases where the power function was impossibly slow to determine that the
-- result is inexact. Thanks Stefan Krah for identifying this problem.
precision: 16
maxExponent: 999999999
minExponent: -999999999
extr1700 power 10 1e-999999999 -> 1.000000000000000 Inexact Rounded
extr1701 power 100.0 -557.71e-742888888 -> 1.000000000000000 Inexact Rounded
extr1702 power 10 1e-100 -> 1.000000000000000 Inexact Rounded
-- A couple of interesting exact cases for power. Note that the specification
-- requires these to be reported as Inexact.
extr1710 power 1e375 56e-3 -> 1.000000000000000E+21 Inexact Rounded
extr1711 power 10000 0.75 -> 1000.000000000000 Inexact Rounded
extr1712 power 1e-24 0.875 -> 1.000000000000000E-21 Inexact Rounded
-- Tests for the is_* boolean operations
precision: 9

76
Lib/test/test_decimal.py
View File

@ -71,10 +71,41 @@ skip_expected = not os.path.isdir(directory)
# list of individual .decTest test ids that correspond to tests that
# we're skipping for one reason or another.
skipped_test_ids = [
'scbx164', # skipping apparently implementation-specific scaleb
'scbx165', # tests, pending clarification of scaleb rules.
]
skipped_test_ids = set([
# Skip implementation-specific scaleb tests.
'scbx164',
'scbx165',
# For some operations (currently exp, ln, log10, power), the decNumber
# reference implementation imposes additional restrictions on the context
# and operands. These restrictions are not part of the specification;
# however, the effect of these restrictions does show up in some of the
# testcases. We skip testcases that violate these restrictions, since
# Decimal behaves differently from decNumber for these testcases so these
# testcases would otherwise fail.
'expx901',
'expx902',
'expx903',
'expx905',
'lnx901',
'lnx902',
'lnx903',
'lnx905',
'logx901',
'logx902',
'logx903',
'logx905',
'powx1183',
'powx1184',
'powx4001',
'powx4002',
'powx4003',
'powx4005',
'powx4008',
'powx4010',
'powx4012',
'powx4014',
])
# Make sure it actually raises errors when not expected and caught in flags
# Slower, since it runs some things several times.
@ -165,27 +196,6 @@ LOGICAL_FUNCTIONS = (
'same_quantum',
)
# For some operations (currently exp, ln, log10, power), the decNumber
# reference implementation imposes additional restrictions on the
# context and operands. These restrictions are not part of the
# specification; however, the effect of these restrictions does show
# up in some of the testcases. We skip testcases that violate these
# restrictions, since Decimal behaves differently from decNumber for
# these testcases so these testcases would otherwise fail.
decNumberRestricted = ('power', 'ln', 'log10', 'exp')
DEC_MAX_MATH = 999999
def outside_decNumber_bounds(v, context):
if (context.prec > DEC_MAX_MATH or
context.Emax > DEC_MAX_MATH or
-context.Emin > DEC_MAX_MATH):
return True
if not v._is_special and v and (
v.adjusted() > DEC_MAX_MATH or
v.adjusted() < 1-2*DEC_MAX_MATH):
return True
return False
class DecimalTest(unittest.TestCase):
"""Class which tests the Decimal class against the test cases.
@ -323,22 +333,6 @@ class DecimalTest(unittest.TestCase):
ans = FixQuotes(ans)
# skip tests that are related to bounds imposed in the decNumber
# reference implementation
if fname in decNumberRestricted:
if fname == 'power':
if not (vals[1]._isinteger() and
-1999999997 <= vals[1] <= 999999999):
if outside_decNumber_bounds(vals[0], self.context) or \
outside_decNumber_bounds(vals[1], self.context):
#print "Skipping test %s" % s
return
else:
if outside_decNumber_bounds(vals[0], self.context):
#print "Skipping test %s" % s
return
if EXTENDEDERRORTEST and fname not in ('to_sci_string', 'to_eng_string'):
for error in theirexceptions:
self.context.traps[error] = 1

4
Misc/NEWS
View File

@ -75,6 +75,10 @@ C-API
Library
-------
- Fix extreme speed issue in Decimal.pow when the base is an exact
power of 10 and the exponent is tiny (for example,
Decimal(10) ** Decimal('1e-999999999')).
- Issue #9130: Fix validation of relative imports in parser module.
- Issue #9128: Fix validation of class decorators in parser module.