From: "David A. Black" <dblack@...>
Date: 2009-07-22T08:01:05+09:00
Subject: Re: Standard Deviation question regarding EDOM errors

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Hi --

On Wed, 22 Jul 2009, Älphä Blüë wrote:

>> The logic in the second snippet is wrong (assuming the logic in the
>> product method is what you want). Try it with [1,2], for example, and
>> you'll get 2 for the first one and 5 for the second.
>>
>>
>> David
>
> Hi David,
>
> Please bear with me as my brain is a bit fried - been working on a lot
> of complex issues all day long and so my mind is mush at this point.  I
> don't quite follow..

The method is calculating "product" as the sum of the squares (which I
don't actually think is the product, is it?). The class's product
method is calculating the product of all the elements of the array. So
they're different.

   [1,2,3].inject {|a,b| a * b }      # 6

   total = 0.0
   [1,2,3].each {|a| total += a * a }
   total                              # 14.0


David

-- 
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