From: Robert Feldt <feldt@...>
Date: 2003-09-16T03:14:05+09:00
Subject: Re: performance and style advice requested

Dave Brown <dagbrown@LART.ca> skrev den Tue, 16 Sep 2003 02:48:04 +0900:

> def fact(x)
> @facts[x] ||= (1..x).inject(1) { |a,i| a*i }
> end

Nice one. With the risc of losing readability here is an even
more efficient one:

@facts = [1]
def fact(n)
  @facts[n] ||= (@facts.last..n).inject(1) {|f, i| @facts[i] = i * f}
end

since you won't need to recalc more than the ones between largest memoized
and your new one. In practice this tweak would probably make
very little difference... ;)

/Robert