Prev: Web Services
Next: ifft from fft (Retrieving signal from a fourier transform using ifft)
From: shahnaz fatima on 1 Aug 2010 10:05
i have a matrix [ 0 -1 0; -1 0 -1 ; 0 -1 0]
its eigenvalues are 0 ,0, 0

i forgot how to find eigenvectors can anyone explain.

anser is ( 1,1,1) (-1 0 1) (1 -2 1)
From: John D'Errico on 1 Aug 2010 10:19
"shahnaz fatima" <shahnaz1981fat(a)gmail.com> wrote in message <i33uuk$cl3$1(a)fred.mathworks.com>...
> i have a matrix [ 0 -1 0; -1 0 -1 ; 0 -1 0]
> its eigenvalues are 0 ,0, 0
>
> i forgot how to find eigenvectors can anyone explain.
>
> anser is ( 1,1,1) (-1 0 1) (1 -2 1)

That is funny, since the eigenvalues are NOT as
you say, nor are those the correct eigenvectors.

help eig

John
From: shahnaz fatima on 1 Aug 2010 10:51
i think the matrix that i assumed is wrong . actually it should be the laplacian of the graph G=(V,E)

where V={1,2,3}
G={(1,2), (2,3).

laplacian is defined as l(i,j)= -1 if (i,j) belongs to E, degree if i=j and zero otherwise.

thats y i assumed it to be like [0 -1 0;-1 0 -1; 0 -1 0]
but i think l(2,2 )is not zero.

can u say what could be that
From: John D'Errico on 1 Aug 2010 12:17
"shahnaz fatima" <shahnaz1981fat(a)gmail.com> wrote in message <i341km$hi$1(a)fred.mathworks.com>...
> i think the matrix that i assumed is wrong . actually it should be the laplacian of the graph G=(V,E)
>
> where V={1,2,3}
> G={(1,2), (2,3).
>
> laplacian is defined as l(i,j)= -1 if (i,j) belongs to E, degree if i=j and zero otherwise.
>
> thats y i assumed it to be like [0 -1 0;-1 0 -1; 0 -1 0]
> but i think l(2,2 )is not zero.
>
> can u say what could be that

I can say that you should do your own homework.

Regardless, we cannot possibly answer a problem
that you cannot even state in the first place.
From: Steven_Lord on 3 Aug 2010 14:01


"shahnaz fatima" <shahnaz1981fat(a)gmail.com> wrote in message
news:i341km$hi$1(a)fred.mathworks.com...
> i think the matrix that i assumed is wrong . actually it should be the
> laplacian of the graph G=(V,E)
>
> where V={1,2,3}
> G={(1,2), (2,3).
>
> laplacian is defined as l(i,j)= -1 if (i,j) belongs to E, degree if i=j
> and zero otherwise.
>
> thats y i assumed it to be like [0 -1 0;-1 0 -1; 0 -1 0]

As the old saying goes, you know what happens when you make an assumption
....

Since this is a small graph, it's easy to construct a picture of the graph.
Do so.
Once you have your picture, reread your definition of "laplacian". Use that
definition to construct the matrix whose eigenvectors and eigenvalues you
want to compute. The picture you drew previously should be of help in the
construction.

> but i think l(2,2 )is not zero.

Okay, so what should it be?

--
Steve Lord
slord(a)mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ
To contact Technical Support use the Contact Us link on
http://www.mathworks.com

 | 
Pages: 1
Prev: Web Services
Next: ifft from fft (Retrieving signal from a fourier transform using ifft)