Re: Summation notation & tensors

From: Tom Roberts (tjroberts_at_lucent.com)
Date: 01/09/05 

Date: Sun, 09 Jan 2005 15:50:02 GMT

Zinc Potterman wrote:
> I understand nested sums but I don't recall seeing three dummy variables
> underneath the sigma symbol before.

Addition is commutative[#], so you can sum over the different dummy
indices in any order.

        [#] OK, there are other mathematical systems in which it isn't
        -- in such systems one cannot use the Einstein summation
        convention, and must write out all sums explicitly.

Tom Roberts tjroberts@lucent.com

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