output from eig() is complex?

[John W. Eaton]

On 19-Jul-1996, Mario Storti <address@hidden> wrote:

: I want to compute the eigenvalues of  a symmetric matrix and sort them
: as real  numbers  but   I  don't  obtained the  expected   result. For
: instance:
: 
: octave:7> A=rand(10);
: octave:8> A=A+A';
: octave:9> sort(eig(A))
: ans =
: 
:    0.0089208
:    0.5152296
:   -0.5608954
:   -0.6509429
:    0.9682804
:    1.5698353
:    1.9441555
:   -2.0148139
:   -2.5246725
:    9.5114825
: 
: My  interpretation is that  Octave is sorting   the vector by absolute
: value since this is the action for complex numbers, and in general the
: result from  the  eig()   operation   should be   a list  of   complex
: numbers.

Correct.

The problem is that Octave 1.1.1 doesn't do automatic type conversions
in some places that it should.  This problem should be fixed in the
next release.

Thanks,

jwe