Eigenvalues and Normalised Eigenvectors

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Homework Help Overview

The discussion revolves around finding the eigenvalues and normalized eigenvectors of a 2x2 matrix defined as H = [h g; g h]. Participants are exploring the concepts of eigenvalues and eigenvectors in the context of linear algebra.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to find eigenvalues by solving the determinant equation and derives the eigenvalues as λ = h ± g. They then seek guidance on how to find the normalized eigenvectors. Other participants suggest substituting the eigenvalues back into the eigenvector equation and normalizing the resulting vectors. There is also a discussion about the correctness of the derived eigenvectors (1,1) and (1,-1) for the respective eigenvalues.

Discussion Status

Participants are actively discussing the normalization of the eigenvectors. While some have provided guidance on the process of finding eigenvectors, there is a lack of consensus on whether the derived vectors are normalized, leading to further questions about the definition of normalization and the unit length of vectors.

Contextual Notes

There is an ongoing exploration of the concept of normalization, with participants questioning the unit length of the derived eigenvectors and discussing the implications of the standard norm.

captainjack2000
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Homework Statement


I have a matrix
H= [h g
g h]
and I need to find the eigenvalues and normalised eigenvectors


Homework Equations





The Attempt at a Solution


I subtracted lamda from the diagonal and then solved for the determinant equally zero. The eigenvalues I found were
(h-lambda)^2=g^2
so (h-lambda)=+/- g
lamdba=h+/-g

but I'm not sure how to find the normalised eigenvectors?
 
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After finding the eigenvalues, plug them back into the equation (A - λ I)x = 0, one by one, to get your eigenvectors. Then normalize them.
 
Thank you very much.

So what I have done is
for eigenvalue h+g I have two equations
hx+gy=hx+gx and gx+hy = hy+gy which gives x=y so eigenvalue h+g has eigenvector (1,1)
and for eigenvalue h-g I have two equations
hx+gy=hx-gx and hx+gy=hy-gy so x=-y so eigenvalue h-g has eigenvector (1,-1)

Is that correct?
 
are these normalised?
 
What does it mean for a vector to be normalized?
 
to be of unit length...which these are right?
 
I am not going to check your calculations, but with respect to the standard norm neither (1, 1) nor (1, -1) have unit length, since |(1, 1)|=(|(1, -1)|) = √2.
 

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