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Homework Help: In the complex field, is this function Harmonic?

  1. Apr 16, 2009 #1
    1. The problem statement, all variables and given/known data
    Without directly verifying via the laplace equations, explain why Log|z| is harmonic in the punctured complex plane.

    2. Relevant equations

    3. The attempt at a solution
    I thought it was because Log z is analytic on the complex plane except for the nonpositive real axis, so Log |z| would be analytic and hence harmonic since any |z| turns z into a positive real (for z=/= 0), hence Log |z| is like Log z for positive reals. But, if it's that, why would they ask to show its harmonic and not analytic.
  2. jcsd
  3. Apr 17, 2009 #2
    Do you have the theorem that if f=u+iv is analytic then u is harmonic?
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