[Python-Dev] Re: Decimal data type issues (original) (raw)

Moore, Paul Paul.Moore at atosorigin.com
Fri Apr 23 05:42:31 EDT 2004

From: Tim Delaney

I think we probably want a supplemental PEP for upgrading the math module plus appropriate builtins (like round) to handle Decimal. A quick scan through the docs reveals

While I'm sure the numerical properties are iffy, just how bad is using binary FP as an intermediate when calculating transcendental functions for Decimal values?

I'm thinking of something like

d = Decimal(...)
f = math.sin(float(d))
# Now convert back using exact float->Decimal, followed by
# context-respecting "+" operation
result = +Decimal.from_float(f)

I suspect that this is adequate for "casual" users. And I'm not at all sure that the target audience for a Decimal type really cares about transcendental functions...

(I think that boils down to claiming YAGNI, at least in the first instance).

Paul.

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