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Diffstat (limited to 'Misc/NEWS')
| -rw-r--r-- | Misc/NEWS | 20 |
1 files changed, 20 insertions, 0 deletions
@@ -3,6 +3,26 @@ What's New in Python 2.2a0? Core +- Float (and complex) literals in source code were evaluated to full + precision only when running from a .py file; the same code loaded from a + .pyc (or .pyo) file could suffer numeric differences starting at about the + 12th significant decimal digit. For example, on a machine with IEEE-754 + floating arithmetic, + + x = 9007199254740992.0 + print long(x) + + printed 9007199254740992 if run directly from .py, but 9007199254740000 + if from a compiled (.pyc or .pyo) file. This was due to marshal using + str(float) instead of repr(float) when building code objects. marshal + now uses repr(float) instead, which should reproduce floats to full + machine precision (assuming the platform C float<->string I/O conversion + functions are of good quality). + + This may cause floating-point results to change in some cases, and + usually for the better, but may also cause numerically unstable + algorithms to break. + - Dictionary objects now support the "in" operator: "x in dict" means the same as dict.has_key(x). |