From: Sebastian Steinlechner <ttt@...>
Date: 2006-02-06T00:44:19+09:00
Subject: Help with "rubyizing" script

Hi list,

I haven't gotten around to do some serious programming with Ruby, but
today I decided to hack up a quick script to help me with calculating
Miller's indices (if you don't know what that is, doesn't matter...).

Unfortunately, it didn't come out quite as nicely as I'd thought/hoped.
Well, here it is:

-- snip --

a = gets.to_i
w = Math.sqrt(a).to_i

(0..w).each do |l|
  (0..l).each do |k|
    (0..k).each do |h|
      print a, ': (', h,k,l,")\n" if (h*h + k*k + l*l) == a
    end
  end
end

-- snap --

First of all, the to_i stuff at the beginning is somewhat ugly. It
probably works without, but I first used w.times, which needs a
Fixnum... then again, a needs to be Fixnum for the if statement to work.

Then I don't really like the (0..x) stuff. As I said, I tried times, but
that only counts up to w-1. Hm. And (w+1).times is even uglier. Anything
better than that? There's probably a better way get a list of all
members of [0..w] x [0..w] x [0..w] ("x" being the cartesian product),
from which one could then select() the ones that fit. Any ideas on that?

Then I don't like the print statement. I thought
print "#{a}: (#{h,k,l})"
might work, but that gives me an error (unterminated string). Why's
that? And
print "#{a}: (#{h}#{k}#{l})"
is again quite clumsy, I'd say.

Oh, and a last thing: I'd rather write a.sqrt and was disappointed this
doesn't work. However, ruby-doc _does_ mention Math#sqrt, and even
Math#sqrt!:
http://ruby-doc.org/core/classes/Math.html#M002069
It took me a while to find out those are from Complex. Would it be
possible to state this more clearly somewhere? Better yet, make a.sqrt work?

Thanks in advance,

Sebastian