[Python-Dev] [RELEASED] Python 3.3.0 release candidate 3

Brett Cannon brett at python.org
Sat Sep 29 20:26:50 CEST 2012


On Sat, Sep 29, 2012 at 9:07 AM, Paul Moore <p.f.moore at gmail.com> wrote:

> On 29 September 2012 10:17, Stefan Krah <stefan at bytereef.org> wrote:
> > Tim Delaney <timothy.c.delaney at gmail.com> wrote:
> >> If those numbers are similar in other benchmarks, would it be accurate
> and/or
> >> reasonable to include a statement along the lines of:
> >>
> >> "comparable to float performance - usually no more than 3x for
> calculations
> >> within the range of numbers covered by float"
> >
> > For numerical programs, 1.4x (9 digits) to 3x (19 digits) slower would be
> > accurate. On Windows the difference is even less.
> >
> > For output formatting, cdecimal is faster than float (at least it was
> when
> > I posted a benchmark a couple of months ago).
>
> To me, this means that the key point is that for the casual user,
> float is no longer the "obvious" choice. You'd choose float for the
> convenience of a built in type, and Decimal for the more natural
> rounding and precision semantics. If you are sufficiently interested
> in performance for it to matter, you're no longer a "casual" user. (Up
> until now, I'd have said use float unless your need for the better
> behaviour justifies the performance loss - that's no longer the case)
>

Does this mean we want to re-open the discussion about decimal constants?
Last time this came up I think we decided that we wanted to wait for
cdecimal (which is obviously here) and work out how to handle contexts, the
syntax, etc.
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