[Python-Dev] Numerical robustness, IEEE etc. (original) (raw)

Facundo Batista facundobatista at gmail.com
Tue Jun 20 20:25:26 CEST 2006

2006/6/20, Nick Coghlan <ncoghlan at gmail.com>:

Nick Maclaren wrote: > Brett Cannon's and Neal Norwitz's replies appreciated and noted, but > responses sent by mail.

Damn, the most difficult way to keep a thread...

The intent was always to replace the internal use of tuples and longs with a more efficient C implementation - that particular step simply wasn't needed for the original use case that lead Facundo to write and implement PEP 327.

Right. We never addressed speed. I mean, we made Decimal as fast as we could in the limited time we had (Raymond H. helped a lot also here), but it was NOT designed for speed.

BTW, prove me Decimal is not fast enough, ;)

Mateusz Rucowicz has taken up the challenge for Google's Summer of Code (mentored by Facundo Batista, the original author of PEP 327 and the decimal module).

I've cc'ed Facundo, so hopefully he will see this thread and chime in :)

I was reading the thread, yes, but it's so difficult to follow when half the messages are not in the list... :(

> Mode A: follow IEEE 754R slavishly, if and when it ever gets into print. > There is no point in following C99, as it is too ill-defined, even if it > were felt desirable. This should not be the default, because of the > flaws I mention above (see Kahan on Java).

See Cowlishaw's specification for how you can configure contexts to achieve different "modes", and reasons for it and all.

Easier way: Just read Decimal docs.

Let's not skip it, because the decimal module already seems to do pretty much what you describe here :)

Well... I think I missed it... but a very good way to resume it would be: Explain us what do you need to do that there's not achievable with Decimal...

Regards,

-- . Facundo

Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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