Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Kronecker Delta

  1. Mar 14, 2010 #1
    1. The problem statement, all variables and given/known data
    Simplify/Evaluate these expressions involving the Kronecker delta, using Einstein's summation convention:

    2. Relevant equations
    [tex]\delta_{ij}[/tex]=0 when i =/= j
    [tex]\delta_{ij}[/tex]=1 when i = j

    3. The attempt at a solution
    =[tex]\delta_{qq}[/tex] = 3 (summation over repeated q)

    [Am I actually able to evaluate the [tex]\delta_{qr}[/tex][tex]\delta_{rq}[/tex] part before the [tex]\delta_{pp}[/tex] part, I mean you can't do that with matrices... :S]

    Thank you
  2. jcsd
  3. Mar 14, 2010 #2


    User Avatar
    Science Advisor

    I think what you did is correct. If you think of them as matrices, remember they are identity matrices, so they commute with everything, so the order does not matter.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook