[Python-Dev] PEP 3188: Implementation Questions

[Mark Dickinson]

On Sun, Feb 28, 2010 at 1:39 AM, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> 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.

I'd be astonished. :)

Mark