From: Tomasz Wegrzanowski <tomasz.wegrzanowski@...>
Date: 2006-08-21T20:03:44+09:00
Subject: Re: You can write Fortran in any language

On 8/21/06, Bil Kleb <Bil.Kleb@nasa.gov> wrote:
> Here is an example used for computing correlations.
> It's almost a direct translation of several hundred
> lines of Fortran 77.
>
> If you can bare to look, please help, even it is simply
> to say "yo bonehead, why didn't you just require 'some_library'?"
[cut]
>    for i in 0..x.size-1

Well, it's a very small thing, but tripple-dot makes is somewhat more readable:

for i in 0...x.size

And I'd actually use x.size.times {|i| }, for loops looks kinda
alien in Ruby code.

Now pieces of code like:
  sum_x = Array.new(x.size){0.0}
  sum_x_sq = Array.new(x.size){0.0}
  for i in 0..x.size-1
    sum_x[i]    = x[i].inject(0) { |sum, e| sum + e }
    sum_x_sq[i] = x[i].inject(0) { |sum, e| sum + e**2 }
  end
can be rewritten to:
  sum_x = (0...x.size).map{|i| x[i].inject(0) { |sum, e| sum + e }}
  sum_x_sq = (0...x.size).map{|i| x[i].inject(0) { |sum, e| sum + e**2 }}
which looks a lot neater imho.
It would look even neater to write:
  sum_x = x.map{|xi| xi.sum}
  sum_x_sj = x.map{|xi| xi.map{|e|e**2}.sum}
but Ruby doesn't have Enumerable#sum by default.

Oh well, you have a few ideas of making the code nicer now :-)

-- 
Tomasz Wegrzanowski [ http://t-a-w.blogspot.com/ ]