From: ptkwt@...1.aracnet.com (Phil Tomson)
Date: 2003-07-20T01:50:43+09:00
Subject: Re: [SNIPPET] Binary counter

In article <pan.2003.07.19.10.53.34.563639@sneakemail.com>,
Simon Strandgaard <0bz63fz3m1qt3001@sneakemail.com> wrote:
>On Sat, 19 Jul 2003 18:04:07 +0900, Brian Candler wrote:
>
>> On Sat, Jul 19, 2003 at 07:26:32AM +0900, Phil Tomson wrote:
>>> You guys are spoiling all my fun with recursive functions ;-)
>> 
>> Sorry. Well for a bit more fun, how about writing a Gray code counter? The
>> characteristic of this sequence is that each number differs from the
>> previous one by exactly one bit.
>
>I found a homepage:  ruby + gray code
>
>http://www.public.asu.edu/~ncban/graycode.html
>

Very nice, compact algorithm there.  

<quote>

"Here's an algorithm for translating binary to Gray code. It's in a loop here, 
but unlike the other algorithms we've looked at, it doesn't have to be. This 
algorithm can convert an arbitrary binary number to Gray code in finite time. 
Wonderful! 

#!/usr/bin/env ruby

bits = 4
(1 << bits).times do |binary|
  grayCode = binary ^ (binary >> 1)
  printf "%0#{bits}b\n", grayCode
end


 How does it work? Beats me. It's magic. "

</quote>


Phil