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[Octave-bug-tracker] [bug #45153] eigs returning an incorrrect number of
From: |
Marco Caliari |
Subject: |
[Octave-bug-tracker] [bug #45153] eigs returning an incorrrect number of eigenvalues |
Date: |
Wed, 29 Mar 2017 14:43:09 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 |
Update of bug #45153 (project octave):
Status: Confirmed => Patch Submitted
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Follow-up Comment #8:
Finally, I have a patch to the stable branch. I think there was already a
tentative to give the exact number of required eigenvalues, but not working,
and buggy in fact. See the new test containing isnan. The same test showed a
differente bug in ARPACK itself (
https://github.com/opencollab/arpack-ng/issues/58).
I also fixed bug #47236, somehow related. Now eigs returns the correct number
of eigenvalues and "essentially" in the same order for the calls [v1,d1] =
eigs(...) and d2 = eigs(...). Some discrepancies are still possible, however,
when conjugate pairs are present. For instance, it is possible that
diag(d1)
ans =
0.88029 + 0.30282i
0.88029 - 0.30282i
-0.69077 + 0.75447i
-0.69077 - 0.75447i
-1.12180 + 0.25552i
and
d2
ans =
-1.12180 - 0.25552i
-1.12180 + 0.25552i
0.88029 + 0.30282i
0.88029 - 0.30282i
-0.69077 - 0.75447i
This is ARPACK. I also allowed p to take the value n (as in Matlab and
ARPACK), since it can speed up the convergence.
Please revise my patch.
(file #40201)
_______________________________________________________
Additional Item Attachment:
File name: eigs_stable.patch Size:24 KB
_______________________________________________________
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<http://savannah.gnu.org/bugs/?45153>
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