[Python-Dev] Floating-point implementations

Steve Holden steve at holdenweb.com
Tue Dec 9 18:43:28 CET 2008

Mark Dickinson wrote:
> On Tue, Dec 9, 2008 at 5:15 PM, Steve Holden <steve at holdenweb.com> wrote:
>> precision than the usual 56-bit mantissa. Do modern 64-bit systems
>> implement anything wider than the normal double?
> I may have misinterpreted your question.  Are you asking simply
> about what the hardware provides, or about what the C compiler
> and library support?  Or something else entirely?
> It looks like IEEE-conforming 128-bit floats would have a 113-bit
> mantissa (including the implicit leading '1' bit).
I was actually asking about Python implementations, and read your
original answer as meaning "no, there aren't any". I had assumed,
correctly or otherwise, that the C library would have to offer
well-integrated support to enable its use in Python. In fact I had
assumed it would need to be pretty much a drop-in repleacement, but it
sounds as though there are some hard-coded assumptions about float size
that would not allow that.

Steve Holden        +1 571 484 6266   +1 800 494 3119
Holden Web LLC              http://www.holdenweb.com/

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