Example 2.  Find the eigenvalues and eigenvectors of the matrix  [Graphics:Images/EigenvaluesMod_gr_111.gif].

Solution 2.

[Graphics:../Images/EigenvaluesMod_gr_112.gif]

[Graphics:../Images/EigenvaluesMod_gr_113.gif]

 

 

[Graphics:../Images/EigenvaluesMod_gr_114.gif]

[Graphics:../Images/EigenvaluesMod_gr_115.gif]

 

 

This is equivalent to the linear system

    [Graphics:../Images/EigenvaluesMod_gr_116.gif]

Set [Graphics:../Images/EigenvaluesMod_gr_117.gif] and solve for  [Graphics:../Images/EigenvaluesMod_gr_118.gif], and get the eigenvector  

 

[Graphics:../Images/EigenvaluesMod_gr_119.gif]

Verify the eigenpair.

[Graphics:../Images/EigenvaluesMod_gr_120.gif]


[Graphics:../Images/EigenvaluesMod_gr_121.gif]


[Graphics:../Images/EigenvaluesMod_gr_122.gif]

[Graphics:../Images/EigenvaluesMod_gr_123.gif]

 

 

This is equivalent to the linear system

    [Graphics:../Images/EigenvaluesMod_gr_124.gif]

Set [Graphics:../Images/EigenvaluesMod_gr_125.gif] and solve for  [Graphics:../Images/EigenvaluesMod_gr_126.gif], and get the eigenvector  

 

[Graphics:../Images/EigenvaluesMod_gr_127.gif]

Verify the eigenpair.

[Graphics:../Images/EigenvaluesMod_gr_128.gif]


[Graphics:../Images/EigenvaluesMod_gr_129.gif]

Remark. Newton's method can be used to find the roots of the characteristic polynomial.

For the first eigenvalue.

[Graphics:../Images/EigenvaluesMod_gr_130.gif]


[Graphics:../Images/EigenvaluesMod_gr_131.gif]

Which is an approximation to the eigenvalue

[Graphics:../Images/EigenvaluesMod_gr_132.gif]

[Graphics:../Images/EigenvaluesMod_gr_133.gif]


For the second eigenvalue.

[Graphics:../Images/EigenvaluesMod_gr_134.gif]


[Graphics:../Images/EigenvaluesMod_gr_135.gif]

Which is an approximation to the eigenvalue

[Graphics:../Images/EigenvaluesMod_gr_136.gif]

[Graphics:../Images/EigenvaluesMod_gr_137.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004