Proposed standard python module: ieee754

[Warnes, Gregory R]

Martin <martin at v.loewis.de> writes:
> 
> I find the name of the package misleading. It sounds like it would
> provide support for IEEE 754, but it doesn't. Instead, it relies
> that the underlying hardware is IEEE 754 compliant. 

It is true that the name could be better.  Given that we have 'fpectl' and
'fpformat', perhaps a better name would be 'fpconst', indicating that it
provides tools for dealing with floating point constants.

> If it were, this module would be nearly irrelevant.

Not at all.  As it stands now, most common platforms have IEEE 754 compliant
hardware, unfortunately, the C library routines are inconsistent in how and
whether they deal with these special values.   Consider the following :

Solaris 8 - UltraSparc - Python 2.2.1 -- compiled with gcc

	>>> float(1e3000)
	Infinity
	>>> float('Inf')
	Infinity

Windows 2000 - Pentium III - ActivePython 2.2.1

	>>> float(1e3000)
	1.#INF	
	>>> float('Inf')
	Traceback (most recent call last):
	  File "<stdin>", line 1, in ?
	ValueError: invalid literal for float(): Inf

Windows 2000 + cygwin - Pentium III - Python 2.2.2

	>>> float(1e3000)
	Inf
	>>> float('Inf')
	Traceback (most recent call last):
	  File "<stdin>", line 1, in ?
	ValueError: invalid literal for float(): Inf

Mac OS/X - PowerPC G4 - Python 2.

	>>> float(1e3000)
	Inf
	>>> float('Inf')
	Traceback (most recent call last):
	  File "<stdin>", line 1, in ?
	ValueError: invalid literal for float(): Inf

As you can see, there is no consistency among C libraries, even on the same
exact OS and CPU.

-Greg


LEGAL NOTICE
Unless expressly stated otherwise, this message is confidential and may be privileged. It is intended for the addressee(s) only. Access to this E-mail by anyone else is unauthorized. If you are not an addressee, any disclosure or copying of the contents of this E-mail or any action taken (or not taken) in reliance on it is unauthorized and may be unlawful. If you are not an addressee, please inform the sender immediately.