From: ara.t.howard@...
Date: 2007-02-02T03:05:09+09:00
Subject: Re: For performance, use Lua

On Fri, 2 Feb 2007, William James wrote:

>
> The results are wrong.  500000.5 is the correct average.  And this is slower
> than pure interpreted Lua (on a 3.19GHz machine).  Try it.
>

the results are right, my code was wrong.  here's the correct translation:

   harp:~ > cat a.rb
   require 'narray'

   time = Time.now

   max_loop = (ARGV.shift || 20).to_i
   max_size = (ARGV.shift || 1_000_000).to_i
   a = NArray.float(max_size).indgen + 1

   total = 0
   max_loop.times { total += a.mean }
   p Time.now - time
   p total, total/max_loop


   harp:~ > ruby a.rb
   0.283084
   10000010.0
   500000.5

>
> So a compiled, very low level, very crude language
> (i.e., C) using low-precision math can beat Lua.
> Not surprising.
>

well, as i just showed - the math is not low precision and it's correct.
remember lua, ruby, luajit, and ruby extensions are all __exactly__ the same
thing, namely very low level very crude c.  in all cases the good thing is that
it's c that someone else has written.  the point is that you need to get into c
to go fast and that there's a variety of ways to do it.  installing narray is
just as good a way to do it as any other.

regards.

-a
-- 
we can deny everything, except that we have the possibility of being better.
simply reflect on that.
- the dalai lama