Solving equations for Eigenvector: Vanishing

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zak100
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Homework Statement


I am trying to solve a Eigen vector matrix:

##\begin{bmatrix}9.2196& 6.488\\4.233& 2.9787\end{bmatrix}\cdot\begin{bmatrix}x\\y\end{bmatrix}-\lambda\begin{bmatrix}x\\y \end{bmatrix}=0##

I have found ##\lambda_1 = 0## and ##\lambda_2 = 12.1983##
However, I can't solve the following equations:
##9.2196x + 6.488y =0 -------(eq.1)##
and ##4.233x + 2.978y =0 ----(eq.2)##

I am multiplying ##(eq.1) ## by ##4.233x## and ##(eq.2)## by ##9.2196##

Some body please guide me how to solve these equations for ##x## and ##y## values.

Zulfi.

Homework Equations


##9.2196x + 6.488y =0 -------(eq.1)##
and ##4.233x + 2.978y =0 ----(eq.2)##​

The Attempt at a Solution


I am multiplying ##(eq.1)## by ##4.233## and ##(eq.2)## by ##9.2196## but both the equations are vanishing. Some body please guide me.

Zulfi.
 
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zak100 said:

Homework Statement


I am trying to solve a Eigen vector matrix:

##\begin{bmatrix}9.2196& 6.488\\4.233& 2.9787\end{bmatrix}\cdot\begin{bmatrix}x\\y\end{bmatrix}-\lambda\begin{bmatrix}x\\y \end{bmatrix}=0##

I have found ##\lambda_1 = 0## and ##\lambda_2 = 12.1983##
However, I can't solve the following equations:
##9.2196x + 6.488y =0 -------(eq.1)##
and ##4.233x + 2.978y =0 ----(eq.2)##

I am multiplying ##(eq.1) ## by ##4.233x## and ##(eq.2)## by ##9.2196##

Some body please guide me how to solve these equations for ##x## and ##y## values.

Zulfi.

Homework Equations


##9.2196x + 6.488y =0 -------(eq.1)##
and ##4.233x + 2.978y =0 ----(eq.2)##​

The Attempt at a Solution


I am multiplying ##(eq.1)## by ##4.233## and ##(eq.2)## by ##9.2196## but both the equations are vanishing. Some body please guide me.

Zulfi.

The two equations are equivalent. So, you just take the solution of either one.
 
Hi,
Thanks for your response. Answer is different in the slide. I have attached the slide. Please guide me.

Slide titled LDA ... Two Classes - Example showing a 2x2 matrix times w1 equals 0 with eigenvalue 0 underneath, a matrix times w2 equals 12.2007 with its eigenvalue, the results w1 = (-0.5755, 0.8178) and w2 = (0.9088, 0.4173) equal w*, and MATLAB code computing invSw, eig of invSw_by_SB, and the projection vector W = V(:,1).
 
Attachments
  • Slide titled LDA ... Two Classes - Example showing a 2x2 matrix times w1 equals 0 with eigenvalue 0 underneath, a matrix times w2 equals 12.2007 with its eigenvalue, the results w1 = (-0.5755, 0.8178) and w2 = (0.9088, 0.4173) equal w*, and MATLAB code computing invSw, eig of invSw_by_SB, and the projection vector W = V(:,1).
    Solving Decimal eq for Eigen vectors LDA vanishing_PicOfSlide.jpg
    37.7 KB · Views: 579
In the solution for ##w_1##, the ratio of the components ##\frac{0.8178}{0.5755}## is the same as the ratio ##\frac{9.2196}{6.488}## in your system of equations. So it's the same answer but with different normalization, one where ##x^2 + y^2 = 1##.
 
Hi,
##lambda_2 =12.1983##
I am not able to get the correct answer.

##9.2196x + 6.488y = 12.1983x ##
##9.216x - 12.1983x = -6.488y ##

##\begin{bmatrix}x\\y\end {bmatrix} = \begin{bmatrix}2.7\\1\end{bmatrix}##

Somebody please guide me how can i get the correct answer?
Zulfi.