Re: Feature suggestion -- return if true

From	Jussi Piitulainen <jpiitula@ling.helsinki.fi>
Newsgroups	comp.lang.python
Subject	Re: Feature suggestion -- return if true
Date	2011-04-19 09:42 +0300
Organization	University of Helsinki
Message-ID	<qot8vv6n3nf.fsf@ruuvi.it.helsinki.fi> (permalink)
References	(4 earlier) <4daaa8a0$0$29986$c3e8da3$5496439d@news.astraweb.com> <BANLkTind9AzzB-WpjLQeW1cnYz=xoUf4dw@mail.gmail.com> <4DAB9C3F.20801@ieee.org> <mailman.493.1303092634.9059.python-list@python.org> <9143muFb0mU1@mid.individual.net>

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Gregory Ewing writes:
> Chris Angelico wrote:
> 
> > Question: How many factorial functions are implemented because a
> > program needs to know what n! is, and how many are implemented to
> > demonstrate recursion (or to demonstrate the difference between
> > iteration and recursion)? :)

(I can't get to the parent directly, so I follow up indirectly.)

Factorials become an interesting demonstration of recursion when done
well. There's a paper by Richard J. Fateman, citing Peter Luschny:

<http://www.cs.berkeley.edu/~fateman/papers/factorial.pdf>
<http://www.luschny.de/math/factorial/FastFactorialFunctions.htm>

Fateman's "major conclusion is that you should probably not use the
'naive' factorial programs for much of anything". I take this to
include their use as examples of recursion, unless the purpose is to
make the idea of recursion look bad.

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Thread

Re: Feature suggestion -- return if true Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-04-17 16:21 +1200
  Re: Feature suggestion -- return if true Chris Angelico <rosuav@gmail.com> - 2011-04-17 14:31 +1000
  Re: Feature suggestion -- return if true Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-17 08:45 +0000
    Re: Feature suggestion -- return if true Chris Angelico <rosuav@gmail.com> - 2011-04-17 19:07 +1000
      Re: Feature suggestion -- return if true Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-17 15:23 +0000
    Re: Feature suggestion -- return if true Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-04-18 12:25 +1200
    Re: Feature suggestion -- return if true Dave Angel <davea@ieee.org> - 2011-04-17 22:04 -0400
    Re: Feature suggestion -- return if true Chris Angelico <rosuav@gmail.com> - 2011-04-18 12:10 +1000
      Re: Feature suggestion -- return if true Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-04-19 12:35 +1200
        Re: Feature suggestion -- return if true Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2011-04-19 09:42 +0300
          Re: Feature suggestion -- return if true Chris Angelico <rosuav@gmail.com> - 2011-04-19 17:01 +1000
  Re: Feature suggestion -- return if true "D'Arcy J.M. Cain" <darcy@druid.net> - 2011-04-17 08:33 -0400
    Re: Feature suggestion -- return if true Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-04-17 15:10 +0000
    Re: Feature suggestion -- return if true aahz@pythoncraft.com (Aahz) - 2011-04-18 09:11 -0700
  Re: Feature suggestion -- return if true Greg Ewing <greg.ewing@canterbury.ac.nz> - 2011-04-18 11:09 +1200

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