[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Octave-bug-tracker] [bug #49523] eigs (R2013b and later) uses NaNs, not
From: |
Rik |
Subject: |
[Octave-bug-tracker] [bug #49523] eigs (R2013b and later) uses NaNs, not zeros, for unconverged Ritz values |
Date: |
Fri, 1 Dec 2017 00:36:15 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:55.0) Gecko/20100101 Firefox/55.0 |
Follow-up Comment #52, bug #49523 (project octave):
Maybe Carlo has an idea on how to relax this. I found that by increasing the
maximum number of iterations, opts.maxit, ARPACK would converge and find all
the eigenvalues. That is not what is needed here.
I restored maxit to 1, and then started changing the initialization vector v0.
For some vectors there was rapid convergence and I got the three eigenvalues
listed in comment #50 (although they were all real, no imaginary parts).
Maybe there is a specific initial vector which is always far enough from a
solution that the answer from comment #46 is obtained.
Otherwise, we could work around it by coding the BIST test like this
if (isreal (d))
assert (d(4), NaN);
else
assert (d(4), NaN+1i*NaN);
endif
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?49523>
_______________________________________________
Message sent via/by Savannah
http://savannah.gnu.org/