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authorChristian Heimes <christian@cheimes.de>2008-01-27 23:50:43 (GMT)
committerChristian Heimes <christian@cheimes.de>2008-01-27 23:50:43 (GMT)
commit26855635833fcd3f15786b4a9d4241ded293404c (patch)
tree37e1984aadfd2e688e7105ce112e3559bf93653e /Lib/rational.py
parent7b69c6c3afba79518865313e1b41845a6b534fb6 (diff)
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Merged revisions 60364-60378 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk ........ r60364 | neal.norwitz | 2008-01-27 19:09:48 +0100 (Sun, 27 Jan 2008) | 4 lines Update the comment and remove the close. If we close we can't flush anymore. We might still need to close after the for loop if flushing 6! times still doesn't cause the signal/exception. ........ r60365 | georg.brandl | 2008-01-27 19:14:43 +0100 (Sun, 27 Jan 2008) | 2 lines Remove effectless expression statement. ........ r60367 | neal.norwitz | 2008-01-27 19:19:04 +0100 (Sun, 27 Jan 2008) | 1 line Try to handle socket.errors properly in is_unavailable ........ r60370 | christian.heimes | 2008-01-27 20:01:45 +0100 (Sun, 27 Jan 2008) | 1 line Change isbasestring function as discussed on the cvs list a while ago ........ r60372 | neal.norwitz | 2008-01-27 21:03:13 +0100 (Sun, 27 Jan 2008) | 3 lines socket.error doesn't have a headers attribute like ProtocolError. Handle that situation where we catch socket.errors. ........ r60375 | georg.brandl | 2008-01-27 21:25:12 +0100 (Sun, 27 Jan 2008) | 2 lines Add refcounting extension to build config. ........ r60377 | jeffrey.yasskin | 2008-01-28 00:08:46 +0100 (Mon, 28 Jan 2008) | 6 lines Moved Rational._binary_float_to_ratio() to float.as_integer_ratio() because it's useful outside of rational numbers. This is my first C code that had to do anything significant. Please be more careful when looking over it. ........ r60378 | christian.heimes | 2008-01-28 00:34:59 +0100 (Mon, 28 Jan 2008) | 1 line Added clear cache methods to clear the internal type lookup cache for ref leak test runs. ........
Diffstat (limited to 'Lib/rational.py')
-rwxr-xr-xLib/rational.py56
1 files changed, 1 insertions, 55 deletions
diff --git a/Lib/rational.py b/Lib/rational.py
index da75ab1..8de8f23 100755
--- a/Lib/rational.py
+++ b/Lib/rational.py
@@ -24,60 +24,6 @@ def gcd(a, b):
return a
-def _binary_float_to_ratio(x):
- """x -> (top, bot), a pair of ints s.t. x = top/bot.
-
- The conversion is done exactly, without rounding.
- bot > 0 guaranteed.
- Some form of binary fp is assumed.
- Pass NaNs or infinities at your own risk.
-
- >>> _binary_float_to_ratio(10.0)
- (10, 1)
- >>> _binary_float_to_ratio(0.0)
- (0, 1)
- >>> _binary_float_to_ratio(-.25)
- (-1, 4)
- """
- # XXX Move this to floatobject.c with a name like
- # float.as_integer_ratio()
-
- if x == 0:
- return 0, 1
- f, e = math.frexp(x)
- signbit = 1
- if f < 0:
- f = -f
- signbit = -1
- assert 0.5 <= f < 1.0
- # x = signbit * f * 2**e exactly
-
- # Suck up CHUNK bits at a time; 28 is enough so that we suck
- # up all bits in 2 iterations for all known binary double-
- # precision formats, and small enough to fit in an int.
- CHUNK = 28
- top = 0
- # invariant: x = signbit * (top + f) * 2**e exactly
- while f:
- f = math.ldexp(f, CHUNK)
- digit = trunc(f)
- assert digit >> CHUNK == 0
- top = (top << CHUNK) | digit
- f = f - digit
- assert 0.0 <= f < 1.0
- e = e - CHUNK
- assert top
-
- # Add in the sign bit.
- top = signbit * top
-
- # now x = top * 2**e exactly; fold in 2**e
- if e>0:
- return (top * 2**e, 1)
- else:
- return (top, 2 ** -e)
-
-
_RATIONAL_FORMAT = re.compile(
r'^\s*(?P<sign>[-+]?)(?P<num>\d+)'
r'(?:/(?P<denom>\d+)|\.(?P<decimal>\d+))?\s*$')
@@ -162,7 +108,7 @@ class Rational(RationalAbc):
(cls.__name__, f, type(f).__name__))
if math.isnan(f) or math.isinf(f):
raise TypeError("Cannot convert %r to %s." % (f, cls.__name__))
- return cls(*_binary_float_to_ratio(f))
+ return cls(*f.as_integer_ratio())
@classmethod
def from_decimal(cls, dec):