Example 4.  Find the eigenvalues and eigenvectors of the matrix  [Graphics:Images/EigenvaluesMod_gr_180.gif].

Solution 4.

Find the characteristic polynomial and the eigenvalues.

[Graphics:../Images/EigenvaluesMod_gr_181.gif]

[Graphics:../Images/EigenvaluesMod_gr_182.gif]

 

 

Investigate the eigen-pairs  [Graphics:../Images/EigenvaluesMod_gr_183.gif]  and   [Graphics:../Images/EigenvaluesMod_gr_184.gif].  

[Graphics:../Images/EigenvaluesMod_gr_185.gif]


[Graphics:../Images/EigenvaluesMod_gr_186.gif]

Introduce the free variables and find the eigenvector.

[Graphics:../Images/EigenvaluesMod_gr_187.gif]

[Graphics:../Images/EigenvaluesMod_gr_188.gif]

 

 

The eigenvalue is repeated, and there are two linearly independent eigenvectors.

Investigate the eigen-pairs  [Graphics:../Images/EigenvaluesMod_gr_189.gif]  and   [Graphics:../Images/EigenvaluesMod_gr_190.gif].  

[Graphics:../Images/EigenvaluesMod_gr_191.gif]


[Graphics:../Images/EigenvaluesMod_gr_192.gif]

For [Graphics:../Images/EigenvaluesMod_gr_193.gif], set  s=0  in  W  and get

[Graphics:../Images/EigenvaluesMod_gr_194.gif]


[Graphics:../Images/EigenvaluesMod_gr_195.gif]

Verify the eigenpair.

[Graphics:../Images/EigenvaluesMod_gr_196.gif]


[Graphics:../Images/EigenvaluesMod_gr_197.gif]

For [Graphics:../Images/EigenvaluesMod_gr_198.gif], set  t=0  in  W  and get

[Graphics:../Images/EigenvaluesMod_gr_199.gif]


[Graphics:../Images/EigenvaluesMod_gr_200.gif]

Verify the eigenpair.

[Graphics:../Images/EigenvaluesMod_gr_201.gif]


[Graphics:../Images/EigenvaluesMod_gr_202.gif]

Investigate the eigen-pair  [Graphics:../Images/EigenvaluesMod_gr_203.gif]

[Graphics:../Images/EigenvaluesMod_gr_204.gif]


[Graphics:../Images/EigenvaluesMod_gr_205.gif]

Introduce the free variables and find the eigenvector.

[Graphics:../Images/EigenvaluesMod_gr_206.gif]

[Graphics:../Images/EigenvaluesMod_gr_207.gif]

 

 

Verify the eigenpair.

[Graphics:../Images/EigenvaluesMod_gr_208.gif]


[Graphics:../Images/EigenvaluesMod_gr_209.gif]

It was good fortune that the three eigenvectors are linearly independent.

[Graphics:../Images/EigenvaluesMod_gr_210.gif]


[Graphics:../Images/EigenvaluesMod_gr_211.gif]

We can compare this with the results obtained using Mathematicas Eigensystem procedure.

[Graphics:../Images/EigenvaluesMod_gr_212.gif]


[Graphics:../Images/EigenvaluesMod_gr_213.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004