Guido van Rossum <guido@digicool.com> writes:
> Here's the third installment -- my response to Moshe's rational
> numbers PEP.
I'm replying to Guido mainly through laziness.
> > PEP: XXX
> > Title: Adding a Rational Type to Python
> > Version: $Revision$
> > Author: pep@zadka.site.co.il (Moshe Zadka)
> > Status: Draft
> > Python-Version: 2.2
> > Type: Standards Track
> > Created: 11-Mar-2001
> > Post-History:
> >
> >
> > Abstract
> >
> > Python has no number type whose semantics are that of a
> > unboundedly precise rational number.
>
> But one could easily be added to the standard library, and several
> implementations exist, including one in the standard distribution:
> Demo/classes/Rat.py.
>
> > This proposal explains the
> > semantics of such a type, and suggests builtin functions and
> > literals to support such a type. In addition, if division of
> > integers would return a non-integer, it could also return a
> > rational type.
>
> It's kind of sneaky not to mention in the abstract that this should be
> the default representation for numbers containing a decimal point,
> replacing most use of floats!
If "/" on integers returns a rational (as I presume it will if
rationals get in as it's the only sane return type), then can we
please have the default way of writing rationals as "p/q"? OK, so it
might be inefficient (a la complex numbers), but it should be trivial
to optimize if required.
Having ddd.ddd be a rational bothers me. *No* langauge does that at
present, do they? Also, writing rational numbers as decimal floats
strikes me s a bit loopy. Is
0.33333333
1/3 or 3333333/10000000?
Certainly, if it's to go in, I'd like to see
> > Literals
> >
> > Literals conforming to the RE '\d*.\d*' will be rational numbers.
in the PEP as justification.
Cheers,
M.
--
MAN: How can I tell that the past isn't a fiction designed to
account for the discrepancy between my immediate physical
sensations and my state of mind?
-- The Hitch-Hikers Guide to the Galaxy, Episode 12
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4