[pypy-issue] [issue792] builtin pow() gives wrong answer

Justin Peel tracker at bugs.pypy.org
Wed Jul 13 10:13:35 CEST 2011

New submission from Justin Peel <peelpy at gmail.com>:

By doing a simple comparison with the Python version of rbitint.py's counterpart 
in CPython, the only difference that I can see is that the constant SHIFT 
(PyLong_SHIFT in CPython) is defined as 31 in pypy and 30 or 15 in CPython 
depending on whether 64-bit integers are supported. I haven't taken the time to 
test if changing the SHIFT value will fix this or not and don't claim to 
understand the 5-ARY exponentiation algorithm, but it is the only discrepancy 
that I could find between the codes.

nosy: +justinpeel
status: unread -> chatting

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