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[Octave-bug-tracker] [bug #34878] eigenvalue problems
From: |
kuo-wei |
Subject: |
[Octave-bug-tracker] [bug #34878] eigenvalue problems |
Date: |
Tue, 22 Nov 2011 13:00:28 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.1 (KHTML, like Gecko) Ubuntu/11.10 Chromium/14.0.835.202 Chrome/14.0.835.202 Safari/535.1 |
URL:
<http://savannah.gnu.org/bugs/?34878>
Summary: eigenvalue problems
Project: GNU Octave
Submitted by: muslim
Submitted on: Tue 22 Nov 2011 01:00:27 PM GMT
Category: Libraries
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect Result
Status: None
Assigned to: None
Originator Name: muslim
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: 3.2.4
Operating System: GNU/Linux
_______________________________________________________
Details:
N=69;
F=fft(eye(N))/sqrt(N);
T=diag([0:floor(N/2),-floor(N/2):-1])*sqrt(2*pi/N);
A=T;
B=real(A-1i*conj(F)*A*F-F*F*A*F*F+1i*F*A*conj(F));
[v,d]=eig(B);
[a,b]=sort(diag(d));
v=v(:,b);
figure
plot(real(a),imag(a),'o');
Consider the above code, there are several problems
1. Executing this code many times(about 5~10) will generate two kinds of image
results!
2. take a look at diag(d), the eigenvalue of B, there are no zero on the
diagonal, but the null(B) is not empty, this is very strange.
3. Execute rank(v) and rank([v,F*v]) now, the answer will be 57 and 56, how
can it be possible?
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?34878>
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