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From: tsg.moore@googlemail.com
Newsgroups: comp.soft-sys.matlab
Subject: Evaluation on branch cuts
Date: Sat, 23 May 2009 07:26:00 -0700 (PDT)
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I always have trouble with Matlab's determination of which value to
use when a function is evaluated on its branch cut. For example,
evaluating the function f(z) = z^(1/2) along the negative real axis.

Is there a way to get Matlab to automatically insert a small imaginary
value in order to keep the signs sorted out? For example, I may want
to use,

f(x + 1e-12*i) as the value of f(x)

That is, other than doing it manually. I suppose my question is are
there any aids to help the programmer keep control over how Matlab is
performing the branch cuts.