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[Octave-bug-tracker] [bug #57185] svds returns inconsistent singular val
From: |
Kai Torben Ohlhus |
Subject: |
[Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values |
Date: |
Fri, 8 Nov 2019 07:10:33 -0500 (EST) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.97 Safari/537.36 |
Update of bug #57185 (project octave):
Severity: 3 - Normal => 4 - Important
Status: Works For Me => Confirmed
Summary: svd returns inconsistent eigenvalues => svds returns
inconsistent singular values
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Follow-up Comment #6:
Now this makes sense, same for default hg_id 959a63d1ede6:
x = randn(10, 5) ;
y = randn(10, 5) ;
z = complex(x, y) ;
[~, Dr] = svds(x);
svds_x = [diag(Dr), svds(x), svd(x)]
[~, Dc] = svds(z);
svd_z = [diag(Dc), svds(z), svd(z)]
isreal(Dr)
arrayfun (@isreal, svd_z)
The output
svds_x =
5.1420 5.1420 5.1420
3.0993 3.0993 3.0993
2.7733 2.7733 2.7733
2.1100 2.1100 2.1100
1.4318 1.4318 1.4318
svd_z =
2.6499 + 0.0000i 7.3784 - 0.0000i 7.3784 + 0.0000i
3.8673 + 0.0000i 5.7718 - 0.0000i 5.7718 + 0.0000i
4.3697 - 0.0000i 4.3697 - 0.0000i 4.3697 + 0.0000i
5.7718 - 0.0000i 3.8673 + 0.0000i 3.8673 + 0.0000i
7.3784 + 0.0000i 2.6499 - 0.0000i 2.6499 + 0.0000i
ans = 1
ans =
0 0 1
0 0 1
0 0 1
0 0 1
0 0 1
Thus two problems:
1. The order of the singular values depends on the number of output arguments
2. The singular values are complex values.
_______________________________________________________
Reply to this item at:
<https://savannah.gnu.org/bugs/?57185>
_______________________________________________
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- [Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues, Muhali, 2019/11/07
- [Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues, Mike Miller, 2019/11/07
- [Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues, Rik, 2019/11/07
- [Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues, Dmitri A. Sergatskov, 2019/11/07
- [Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues, Kai Torben Ohlhus, 2019/11/07
- [Octave-bug-tracker] [bug #57185] svd returns inconsistent eigenvalues, Muhali, 2019/11/08
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values,
Kai Torben Ohlhus <=
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values, Rik, 2019/11/08
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values, Rik, 2019/11/08
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values, Rik, 2019/11/08
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values, Rik, 2019/11/09
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values, Rik, 2019/11/09
- [Octave-bug-tracker] [bug #57185] svds returns inconsistent singular values, Rik, 2019/11/09
- [Octave-bug-tracker] [bug #57185] eigs does not consistently order eigenvalues, Rik, 2019/11/09
- [Octave-bug-tracker] [bug #57185] eigs does not consistently order eigenvalues, Rik, 2019/11/14
- [Octave-bug-tracker] [bug #57185] eigs does not consistently order eigenvalues, Rik, 2019/11/14
- [Octave-bug-tracker] [bug #57185] eigs does not consistently order eigenvalues, Rik, 2019/11/14