[Octave-bug-tracker] [bug #33135] nthroot failure for complex inputs

[Pascal Dupuis]

URL:
  <http://savannah.gnu.org/bugs/?33135>

                 Summary: nthroot failure for complex inputs
                 Project: GNU Octave
            Submitted by: cdemills
            Submitted on: jeu. 21 avril 2011 10:04:45 GMT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: Pascal Dupuis
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.2.4
        Operating System: GNU/Linux

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Details:

Some peoples need basic math lessons.

 (nthroot(1+j, 5))^5
ans = -0.077760 - 0.077760i

at nthroot.m line 62:
 y = abs (x) .^ (1/n) .* sign (x);

This is valid only if x is real ! In case of complex numbers, the value is
y = abs(x).^(1/n) .* exp(j*arg(x)/n))

Regards

Pascal




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