1. SEMINAR ON EIGENVALUESSEMINAR ON EIGENVALUES
AND EIGENVECTORSAND EIGENVECTORS
By
Vinod Srivastava
M.E. Modular I & C
Roll No.151522
2. CONTENTSCONTENTS
Introduction to Eigenvalues and Eigenvectors
Examples
Two-dimensional matrix
Three-dimensional matrix
• Example using MATLAB
• References
3. INTRODUCTIONINTRODUCTION
Eigen Vector-
In linear algebra , an eigenvector or characteristic vector of a square
matrix is a vector that does not changes its direction under the
associated linear transformation.
In other words – If V is a vector that is not zero, than it is an
eigenvector of a square matrix A if Av is a scalar multiple of v.
This condition should be written as the equation:
AV= λv
4. Contd….Contd….
Eigen Value-
• In above equation λ is a scalar known as the eigenvalue or
characteristic value associated with eigenvector v.
• We can find the eigenvalues by determining the roots of the
characteristic equation-
0=− IA λ
5. ExamplesExamples
Two-dimensional matrix example-
Ex.1 Find the eigenvalues and eigenvectors of matrix A.
Taking the determinant to find characteristic polynomial A-
It has roots at λ = 1 and λ = 3, which are the two eigenvalues of A.
=
21
12
A
⇒=− 0IA λ 0
21
12
=
−
−
λ
λ
043 2
=+−⇒ λλ
6. Eigenvectors v of this transformation satisfy the equation,
Av= λv
Rearrange this equation to obtain-
For λ = 1, Equation becomes,
which has the solution,
( ) 0=− vIA λ
( ) 0=− vIA
=
0
0
11
11
2
1
v
v
−
=
1
1
v
7. For λ = 3, Equation becomes,
which has the solution-
Thus, the vectors vλ=1 and vλ=3 are eigenvectors of A associated with the
eigenvalues λ = 1 and λ = 3, respectively.
( ) 03 =− uIA
=
−
−
0
0
11
11
2
1
u
u
=
1
1
u
8. Three-dimensional matrix example-
Ex.2 Find the eigenvalue and eigenvector of matrix A.
the matrix has the characteristics equation-
−
−
−
=
200
130
014
A
( )( )( ) 0234
200
130
014
=+++=
+
−+
−+
=−
λλλ
λ
λ
λ
λ AI
9. therefore the eigen values of A are-
For λ = -2, Equation becomes,
which has the solution-
4,3,2 321 −=−=−= λλλ
( )
=
−
−
=−
0
0
0
000
110
012
0
3
2
1
11
v
v
v
vAIλ
=
2
2
1
v
10. Similarly for λ = -3 and λ = -4 the corresponding eigenvectors u and x are-
=
=
0
0
2
,
0
1
1
xu