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Cross term gives the autocorrelation?

  1. Aug 22, 2008 #1
    I am reading a research paper about "narrow" autocorrelation and
    at the beginning there is an expression I don't unterstand

    http://www.wellesley.edu/Physics/brown/pubs/acv85_P1595-P1601.pdf" [Broken]

    Does someone know what is meant with the word cross term?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Aug 22, 2008 #2


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    Science Advisor

    When you expand (a+b)2, it becomes a2 +2ab +b2.

    The term 2ab is the cross term. What you want is gotten by expanding the integrand to get 3 integrals and using the middle one, omitting the 2.
  4. Aug 23, 2008 #3
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