From: Guillaume Marcais <guslist@...>
Date: 2005-03-28T21:46:31+09:00
Subject: Re: Convert a Hash into an Array

"Mathieu Bouchard" <matju@sympatico.ca> schrieb im Newsbeitrag 
news:Pine.LNX.4.21.0503262110380.5161-100000@mondrian.artengine.ca...
>
> On Fri, 18 Mar 2005, Phrogz wrote:
>> Aside - whatever the name, what an excellent, versatile function! For
>> example, the linked-to geometric series sum at
>> http://www.brpreiss.com/books/opus8/programs/pgm02_06.txt can be
>> written in a more terse and (IMO) more ruby-esque way as simply:
>> def geometric_series_sum( x, n )
>> (0..n).inject(0){ |sum,i| sum+x**i }
>> end
>
> And even shorter,
>
> def geometric_series_sum(x,n) (x**(n+1)-1)/(x-1) end
>

To be very picky:

def geometric_series_sum(x,n) (x==1) ? n+1 : (x**(n+1)-1)/(x-1) end

But given how good the original implementation is (it calculates the 
power with a loop, restarting from 1 for every n...), almost anything 
is an improvement.

Guillaume.