[Octave-bug-tracker] [bug #34251] When I use fzero to determine the roots around 0.5 for tan (x) - sqrt ((1 / x) - 1) I get a non zero complex part

[Pierre-Sandre Farrugia]

URL:
  <http://savannah.gnu.org/bugs/?34251>

                 Summary: When I use fzero to determine the roots around 0.5
for tan (x) - sqrt ((1 / x) - 1)  I get a non zero complex part
                 Project: GNU Octave
            Submitted by: pierresandre
            Submitted on: Thu 08 Sep 2011 03:00:44 PM GMT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Inaccurate Result
                  Status: None
             Assigned to: None
         Originator Name: pierresandre
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.2.4
        Operating System: Microsoft Windows

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Details:

Hi,

I have tried to find the roots of an equation using the following

fun=@(x) tan (x) - sqrt ((1 / x) - 1)
fzero(fun,0.5)

The result is,

6.4171e-001 - 1.4264e-018i

Hence the result contains a non zero imaginary part. While the imaginary part
is effectively zero it might be desirable to avoid having it.

Thank you





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