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Re: new snapshot?
From: |
John W. Eaton |
Subject: |
Re: new snapshot? |
Date: |
Thu, 25 Feb 2010 16:25:45 -0500 |
On 25-Feb-2010, John W. Eaton wrote:
| On 25-Feb-2010, Jaroslav Hajek wrote:
|
| | The ARPACK failures are mysterious. Technically what has changed are
| | the 1D constructors and 1D resize. I scanned through eigs-base.cc and
| | eigs.cc but couldn't spot any problems. I'll try to compile a 64-bit
| | ARPACK and also give it a shot, but right now it's more important for
| | me to get the legends in FLTK backend.
|
| Don't worry about the ARPACK problems. I think I found the reason for
| the failure.
I checked in the following change:
http://hg.savannah.gnu.org/hgweb/octave/rev/b4f67ca318d8
That fixed all the eigs failures for me, but I'm still seeing the
following failure in svds, which uses eigs:
>>>>> processing /export/home/jwe/src/octave/scripts/sparse/svds.m
***** testif HAVE_ARPACK
[u2,s2,v2,flag] = svds(a,k,0);
s2 = diag(s2);
assert(flag,!1);
assert(s(k:-1:1), s2, 1e-10);
!!!!! test failed
assert (s (k:-1:1),s2,1e-10) expected
38.060
38.060
38.034
38.034
38.015
38.015
38.004
but got
38.060
38.034
38.034
38.015
38.015
38.004
38.004
maximum absolute error 0.0263523 exceeds tolerance 1e-10
The test is:
n = 100;
k = 7;
a =
sparse([3:n,1:n,1:(n-2)],[1:(n-2),1:n,3:n],[ones(1,n-2),0.4*n*ones(1,n),ones(1,n-2)]);
[u,s,v] = svd(full(a));
s = diag(s);
[dum, idx] = sort(abs(s));
s = s(idx);
u = u(:,idx);
v = v(:,idx);
randn('state',42)
[u2,s2,v2,flag] = svds(a,k,0);
s2 = diag(s2);
assert(flag,!1);
assert(s(k:-1:1), s2, 1e-10);
If I run this test in a copy of Octave compiled *without* --enable-64,
I sometimes see also the error now. The problem does not happen every
time I run the test. So it seems like some kind of memory error, but
valgrind is not telling me anything.
I'm compiling with CXXFLAGS=-ggdb3 CFLAGS=-ggdb3, GCC version 4.4.3
20100108 (prerelease) (Debian 4.4.2-9) on an amd64 system.
Can anyone else duplicate this problem?
jwe
- new snapshot?, Jaroslav Hajek, 2010/02/18
- Re: new snapshot?, Ben Abbott, 2010/02/18
- new snapshot?, John W. Eaton, 2010/02/18
- Re: new snapshot?, Jaroslav Hajek, 2010/02/18
- Re: new snapshot?, John W. Eaton, 2010/02/18
- Re: new snapshot?, David Bateman, 2010/02/18
- Re: new snapshot?, John W. Eaton, 2010/02/24
- Re: new snapshot?, Jaroslav Hajek, 2010/02/25
- Re: new snapshot?, John W. Eaton, 2010/02/25
- Re: new snapshot?,
John W. Eaton <=
- Re: new snapshot?, Søren Hauberg, 2010/02/25
- Re: new snapshot?, Michael D. Godfrey, 2010/02/26
- Re: new snapshot?, John W. Eaton, 2010/02/26
- Re: new snapshot?, Michael D. Godfrey, 2010/02/26
- Re: new snapshot?, Jaroslav Hajek, 2010/02/26
- Re: new snapshot?, Michael D. Godfrey, 2010/02/26
- Re: new snapshot?, John W. Eaton, 2010/02/26
- Re: new snapshot?, Michael D. Godfrey, 2010/02/26
- Re: new snapshot?, Michael D. Godfrey, 2010/02/26
- Re: new snapshot?, Michael D. Godfrey, 2010/02/26