[Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues

[Muhali]

URL:
  <https://savannah.gnu.org/bugs/?57185>

                 Summary: svd returns inconsistent eigenvalues
                 Project: GNU Octave
            Submitted by: muhali
            Submitted on: Thu 07 Nov 2019 03:19:07 AM PST
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 5.1.0
        Operating System: GNU/Linux

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Details:


x = randn(10, 5) ;
y = randn(10, 5) ;
z = complex(x, y) ;

[~, Dr] = svd(x) ; diag(Dr)
svd(x)
[~, Dc] = svd(z) ; diag(Dc)
svd(z)

isreal(Dr)
isreal(Dc)


This shows that in the complex case, the ordering depends on having explicit
output (Dz) or not. This is inconsistent and also different from Matlab.

svd should also return real and not complex eigenvalues.




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