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If $f:D\to D’$ is analytic and $u: D'\to R$ is harmonic then the composition of $u$ and $f$ is harmonic in $D$.

How can I show that the above statement is true/false? Can anyone help me?

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    Is $f$ an analytic vector field?2012-11-23
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    Why should? Of $D = D' = \mathbb R^d$, then $u = \mathrm{id}$ is harmonic, but not any analytic function $f = f \circ u$ is.2012-11-23
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    @martini: The OP is looking at $u \circ f$. $u=\text{Id}$ doesn't make sense here...2012-11-23
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    This question was already discussed [here](http://math.stackexchange.com/questions/151827/composition-of-a-harmonic-function)...2012-11-23

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