[Python-Dev] PEP 3188: Implementation Questions

[Greg Ewing]

Meador Inge wrote:

> Even with the user-defined precision capabilities of the 'Decimal' 
> class?  In other words, can I create an instance of a 'Decimal' that 
> behaves (in all operations: arithmetic, comparison, etc...) exactly as 
> the extended double precision type offered by a given machine?

It's not precision that's the issue, it's that the number
base is different. That affects which numbers can
be represented exactly, and how results that can't be
represented exactly are rounded.

I would be very surprised if there is a way of configuring
the Decimal type so that it gives identical results to that
of any IEEE binary floating point type, including rounding
behaviour, denormalisation, etc.

-- 
Greg