[Octave-bug-tracker] [bug #45080] normest does not work with sparse complex matrices

[Rik]

Update of bug #45080 (project octave):

                  Status:                    None => Fixed                  
             Open/Closed:                    Open => Closed                 
                 Release:                   3.8.2 => 4.0.0-rc4              

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Follow-up Comment #1:

I think the idea behind using trace() was to have some value that was
correlated with the matrix and that was quick to calculate.  The problem I see
with using just a single value of the matrix (A(1,1)) is that this is likely
to be the same value for millions of sparse matrices (it will be 0 since the
matrix is sparse and only a few entries are non-zero).

I did a benchmark with 


s = sprand (1e5, 1e5, 1e-7)
tic; y = trace (s); toc
Elapsed time is 0.00295806 seconds.


The time, 3 milliseconds, just isn't that significant.

I think the best choice is to convert the single trace value to full.  I made
that change here (http://hg.savannah.gnu.org/hgweb/octave/rev/cc5ffacb15ab).



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