From: rashworth <rashworth@...>
Date: 2001-03-17T13:34:07+09:00
Subject: [ruby-talk:12761] Re: Sum of Squares

Thanks for your code.  ERA

---------- Original Message ----------------------------------
From: Mathieu Bouchard <matju@sympatico.ca>
Reply-To: ruby-talk@ruby-lang.org
Date: Fri, 16 Mar 2001 02:14:51 +0900

>On Tue, 13 Mar 2001, rashworth wrote:
>> Thank you for your note. The new coding worked just fine.
>> Do you have some code for the Sum of the Cross-Products?
>> Sumxy = (x1 * y1) + (x2 * y2) + ....
>
>That is called a dot product, not a "sum of cross-products". Unfortunately
>you can't run two iterators at once easily, but you can still write:
>
>class Array
>	def dot(other)
>		# other.type == Array
>		# other.length == self.length
>		sum = 0
>		length.times {|i| sum += self[i]*other[i] }
>		sum
>	end
>end
>
>(not tested)
>
>matju
>
>