# Suffix Notation

• March 6th 2008, 10:30 AM
Yerobi
Suffix Notation
Simplify delta(ij)delta(ij). The (ij) parts should be read as subscripts to the delta.

Can anyone give me any guidance on how to do this?
• March 6th 2008, 12:12 PM
topsquark
Quote:

Originally Posted by Yerobi
Simplify delta(ij)delta(ij). The (ij) parts should be read as subscripts to the delta.

Can anyone give me any guidance on how to do this?

$\delta_{ij} \delta_{ij} = \sum_{i,j = 1}^n \delta_{ij} \delta_{ij}$
by the Einstein convention.

Now, you know that $\delta_{ij} = 1$ only if i = j, so what is the sum of this series? (ie. how many times in the above sum do we get i = j?)

-Dan
• March 6th 2008, 04:54 PM
Yerobi
'n' number of times?
• March 9th 2008, 05:25 AM
Yerobi
I'm just a bit confused on what form the answer should take? Will it be a constant?