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[Octave-bug-tracker] [bug #54179] sparse/eigs.m test failure
From: |
Andrew Janke |
Subject: |
[Octave-bug-tracker] [bug #54179] sparse/eigs.m test failure |
Date: |
Mon, 25 Jun 2018 05:54:59 -0400 (EDT) |
User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.87 Safari/537.36 |
Follow-up Comment #6, bug #54179 (project octave):
Under Octave 4.4.0 built against arpack 3.6.1 on macOS 10.13.5:
If I take the following test in eigs.m at lines 1439 through 1446:
%! A = toeplitz ([0, 1, zeros(1, 8)], [0, -1, zeros(1, 8)]);
%! A = kron (A, eye (10)) + kron (eye (10), A);
%! Afun = @(x) A * x;
%! opts.v0 = (1:100)';
%! opts.maxit = 5;
%! warning ("off", "Octave:eigs:UnconvergedEigenvalues", "local");
%! d = eigs (Afun, 100, 4, "lm", opts);
%! assert (d(3:4), [NaN+1i*NaN; NaN+1i*NaN]);
and decrease opts.maxit from 5 to 4, then the test passes.
octave:12> test eigs
PASSES 182 out of 182 tests
If I decrease opts.maxit further to 3, I get a different error, `eigs: error
-14 in dneupd`:
octave:10> test eigs
***** testif HAVE_ARPACK
A = toeplitz ([0, 1, zeros(1, 8)], [0, -1, zeros(1, 8)]);
A = kron (A, eye (10)) + kron (eye (10), A);
Afun = @(x) A * x;
opts.v0 = (1:100)';
opts.maxit = 3;
warning ("off", "Octave:eigs:UnconvergedEigenvalues", "local");
d = eigs (Afun, 100, 4, "lm", opts);
assert (d(3:4), [NaN+1i*NaN; NaN+1i*NaN]);
!!!!! test failed
eigs: error -14 in dneupd
This seems to agree with your analysis.
I am no math expert, so I am unable to evaluate these numbers as to
correctness.
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