[Bug-gsl] [bug #47347] Complex tangent failure for -1000i

[M Welinder]

URL:
  <http://savannah.gnu.org/bugs/?47347>

                 Summary: Complex tangent failure for -1000i
                 Project: GNU Scientific Library
            Submitted by: terra
            Submitted on: Sat 05 Mar 2016 10:37:23 PM GMT
                Category: Runtime error
                Severity: 3 - Normal
        Operating System: Linux
                  Status: None
             Assigned to: None
             Open/Closed: Open
                 Release: 2.1
         Discussion Lock: Any

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Details:

With a large negative imaginary component of the argument,
the code for complex tangent ends up doing inf/inf.

tan(-1000i) produces nan-nan*i for me.

tan(1000i) produces i just fine.

Suggestion: use tan(z)=conj(tan(conj(z))) whenever Im(z)<=-1.





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