[Octave-bug-tracker] [bug #41453] norm is really slow for sparse matrices

[Massimiliano Fasi]

Follow-up Comment #15, bug #41453 (project octave):

Well, I think you are right in both cases. I was looking at the patch just as
an improvement of norm (), but I see now that's not the way I should.
Moreover, if the benchmark is svds (A, 1) there's no use in making comparisons
with the version I submitted. For a 8000 x 8000 matrix I compute 16000
eigenvalues, that requires for sure much more time than computing just the
largest magnitude eigenvalue as svds (A, 1) does (it's indeed even faster than
norm (full(A))). Also the remark about full matrices is absolutely right, but
this issue should be fixed for free using ARPACK.

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