bugGNU Octave - Bugs: bug #29829, eigvalues are incorrect

 
 

bug #29829: eigvalues are incorrect

Submitted by:  nos <nosnos>
Submitted on:  Sat 08 May 2010 10:24:21 PM UTC  
 
Category: NoneSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: InvalidAssigned to: None
Originator Name: nosOpen/Closed: Closed
Release: 3.2.3Operating System: GNU/Linux

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Sat 08 May 2010 11:04:59 PM UTC, comment #1:

There seem to be some syntax errors in your example code. I think I fixed them, because I'm able to reproduce the Matlab result with Octave 3.2.4 and the current development sources on my Debian system.

I suspect the problem is in your copy of LAPACK. What version do you have?

On my system, I have

liblapack.so.3gf => /usr/lib/atlas/liblapack.so.3gf

from the package libatlas3gf-base, version 3.6.0-24.

I'm closing this bug report.

John W. Eaton <jwe>
Project Administrator
Sat 08 May 2010 10:24:21 PM UTC, original submission:

eig(rho) gives singular values something like (it even varies from time to time)

-7.1985e+167
-2.2305e-03
2.2305e-03
7.1985e+167

while matlab gives

0.0250
0.0250
0.0250
0.9250

The matrix rho is constructed as follows

I = sqrt(-1);

t0 = eye(2);

t1 = [0 1;
1 0];
t2 = [0 -I;
I 0];
t3 = [1 0;
0 -1];

m1 = [t1,zeros(2);zeros(2),t1];
m2 = [t2,zeros(2);zeros(2),t2];
m3 = [t3,zeros(2);zeros(2),t3];
m4 = [zeros(2),eye(2);eye(2),zeros(2)];
m5 = [zeros(2),t1;t1,zeros(2)];
m6 = [zeros(2),t2;t2,zeros(2)];
m7 = [zeros(2),t3;t3,zeros(2)];
m8 = [zeros(2),-Ieye(2);Ieye(2),zeros(2)];
m9 = [zeros(2),-It1;It1,zeros(2)];
m10 = [zeros(2),-It2;It2,zeros(2)];
m11 = [zeros(2),-It3;It3,zeros(2)];
m12 = [eye(2),zeros(2);zeros(2),-eye(2)];
m13 = [t1,zeros(2);zeros(2),-t1];
m14 = [t2,zeros(2);zeros(2),-t2];
m15 = [t3,zeros(2);zeros(2),-t3];

n=[ 0.0011057
-0.1341262
0.8377961
0.6086926
0.0829238
-0.2919701
0.6070342
-0.1736753
0.2884966
0.0829238
-0.1736753
-0.5649987
-0.0011057
-0.1263867
-0.6271805
];

rho = (eye(4) + n(1)m1+n(2)m2+n(3)m3+n(4)m4+n(5)m5+n(6)m6+n(7)m7+n(8)m8+n(9)m9+n(10)m10+n(11)m11+n(12)m12+n(13)m13+n(14)m14+n(15)*m15)/4

nos <nosnos>

 

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Attach File(s):
   
   
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Attached Files
file #20485:  test.m added by nosnos (1KiB - application/mathematica)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by jwe (Posted a comment)
  • -unavailable- added by nosnos (Submitted the item)
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    Follow 3 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 08 May 2010 11:04:59 PM UTCjweStatusNone=>Invalid
      Open/ClosedOpen=>Closed
    Sat 08 May 2010 10:26:06 PM UTCnosnosAttached File-=>Added test.m, #20485

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