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Einstein Notation

  1. Jul 4, 2009 #1
    From what I'm reading, Xj = aijXi (X is a vector and the subscript for a is i)...though I'm not sure where the aijXi came from. Would this by any chance be a relation for the transformation equations from Xj to Xi?
    Last edited: Jul 4, 2009
  2. jcsd
  3. Jul 4, 2009 #2


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    Yes, [itex]x^j[/itex] and [itex]\underline{x}^i[/itex] are vectors. [itex]a_i^j[/itex] is a mixed tensor of order 2. It's not clear to me what you mean by "given a vector summation" but on the right side of the equation there certainly is a summation: The "Einstein convention" is that when an index is repeated, once as a subscript and once as a superscript, you sum over all values of that index.
  4. Jul 4, 2009 #3
    I see. Thanks for the assistance.
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