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Homework Statement
Homework Equations
The relevant equation is that sqrt(z) = e^(1/2 log z) and the principal branch is from (pi, pi]
The Attempt at a Solution
The solution is provided, since this isn't a homework problem (I was told to post it here anyway). I don't understand why the number z^2 + 1 crosses the negative real halfline in the counterclockwise direction as z crosses (i, i inf). Is it because z^2 + 1 where z = i is 0? I would think the argument of z^2 + 1 should be around pi in order to cross the negative real half line, but I'm not sure. Also, I'm not sure how they said the value jumps from it to it when the half lines are crossed.
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