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Homework Help: Vector mean value - help

  1. Feb 18, 2008 #1
    vector mean value - help!!

    1. The problem statement, all variables and given/known data

    Let n = (n_1, n_2, n_3) be a random unit vector in Descartes coordinates in the 3-dimensional space.

    What is the mean value (or expectation value) of n_i*n_j, where i,j = 1,2,3.

    Or shortly: < n_i*n_j > = ?
  2. jcsd
  3. Feb 18, 2008 #2
    Welcome To Pf.

    Pls Show Some Work.
  4. Feb 18, 2008 #3
    i think, this mean value is a tensor of 3x3
  5. Feb 18, 2008 #4


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    Science Advisor

    Why do you think that? You still haven't shown any work.
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