[issue13060] allow other rounding modes in round()
report at bugs.python.org
Thu Sep 29 19:14:19 CEST 2011
Stefan Krah <stefan-usenet at bytereef.org> added the comment:
> If the C accelerator for decimal gets decimal performance close to
> floats (which I doubt, because it has to do much more), it could be
> very useful for me. What is its estimated time to completion?
It is finished and awaiting review (See #7652). The version in
is the same as the version that will be released as cdecimal-2.3
in a couple of weeks.
Benchmarks for cdecimal-2.2 are over here:
Typically cdecimal is 2-3 times slower than floats. With
further aggressive optimizations one *might* get that down
to 1.5-2 times for a fixed width Decimal64 type, but this is
pure speculation at this point.
If you look at http://www.bytereef.org/mpdecimal/benchmarks.html#mandelbrot-64-bit ,
you'll see that the Intel library performs very well for that specific
type. Exact calculations are performed in binary, then converted to
decimal for rounding. Note that this strategy _only_ works for
relatively low precisions.
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