# Thread:

1. ## Complex Analysis

Determine, with motivation, all funtions that is analytic on
{z/ |z| < 4}, with f( 0 ) = i and |f( z ) <= 1 on {z/ |z| < 4}

2. Originally Posted by JacquesRoux
Determine, with motivation, all funtions that is analytic on
{z/ |z| < 4}, with f( 0 ) = i and |f( z ) <= 1 on {z/ |z| < 4}
It seems your problem is faulty somehow. Because the way it is stated $f(z) = i$ is the only such mapping. Because if $f$ is non-constant then by the open mapping theorem $f(0)$ has to be a mapped into an interior point of the range of $f$ but that is not possible since $f(0)=i$ is a boundary point. Thus, we conclude that constant functions are the only such functions, thus, $f(z) = i$ for all $|z|<4$.

3. Thanks for your help!

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