[Python-Dev] [Python-checkins] r64424 - in python/trunk:Include/object.h Lib/test/test_sys.py Misc/NEWSObjects/intobject.c Objects/longobject.c Objects/typeobject.cPython/bltinmodule.c

[Mark Dickinson]

On Thu, Jun 26, 2008 at 8:55 PM, "Martin v. Löwis" <martin at v.loewis.de>
wrote:

>
> I think the feature is misguided in the first place. Why do you want
> a hex representation of floating point numbers?


Answering for myself:  because it gives an exact representation of a
floating-point number in a fairly human-readable format.


> Can't you use struct.pack for that?


struct.pack would only show the bit layout, leaving the user to
manually extract the sign bit, exponent, and fraction, and then make
sense of the whole thing.  The proposed feature works at a higher
level of abstraction, directly describing the *value* of the float rather
than its bit layout.  In particular, this means it'll make sense
across platforms, regardless of variations in bit layout.

And, if bin/hex/oct are useful, why not base
> 6 (say)?
>

I'd say that bin and hex are special:  bin is natural because
floats are usually thought of, and stored as, binary numbers.
hex is special because it gives a compact way of representing
a float, and because there's already a history of using hex
floats in numerical analysis literature and in programming
languages (C99, Java, ...)

I have to admit that I can't see much use for octal floats.

Mark
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-dev/attachments/20080626/3f79e019/attachment-0001.htm>