[Python-Dev] [Python-checkins] cpython: Issue #7652: Integrate the decimal floating point libmpdec library to speed (original) (raw)

Stefan Krah stefan at bytereef.org
Fri Mar 23 11:40:05 CET 2012

Victor Stinner <victor.stinner at gmail.com> wrote:

By the way, how much faster is cdecimal? 72x or 80x? http://docs.python.org/dev/whatsnew/3.3.html#decimal

It really depends on the precision. Also, the performance of decimal.py depends on many other things in the Python tree, so it easily changes +-10%. Currently, decimal.py seems to be 10% faster than in 3.2, maybe because of the new string representation.

The 80x is a ballpark figure for the maximum expected speedup for standard numerical floating point applications.

factorial(1000) is 219x faster in _decimal, and with increasing precision the difference gets larger and larger.

For huge numbers _decimal is also faster than int:

factorial(1000000):

_decimal, calculation time: 6.844487905502319 _decimal, tostr(): 0.033592939376831055

int, calculation time: 17.96010398864746 int, tostr(): ... still running ...

Stefan Krah

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