Eigenvalue & Eigenvector


Eigenvalue & Eigenvector

Have you ever heard the crazy names eigenvalue & eigenvector ? probably you have found that in maths (matrices).
i have solved many problems of matrices without even knowing what exactly this means & what is the real life application of it.

some of applications are :-
  • Face recognition system (biometric system) which is based on Principle Components Analysis (PCA)
  • Vibration analysis
  • Google page-rank algorithm and many more...
What is Eigenvalue & Eigenvector ?

a matrix acts on a vector by changing both its magnitude and its direction. However, a matrix may act on certain vectors by changing only their magnitude, and leaving their direction unchanged (or possibly reversing it). These vectors are the eigenvectors of the matrix. A matrix acts on an eigenvector by multiplying its magnitude by a factor, which is positive if its direction is unchanged and negative if its direction is reversed. This factor is the eigenvalue associated with thateigenvector

Definition

If A is an n × n matrix, then a nonzero vector x in Rn is called an eigenvector of A if Ax is a scalar multiple of   x;that is ,

Ax= λx

 for some scalar λ. The scalar λ is called an eigenvalue of A , and x is called the eigenvector
of A corresponding to the eigenvalue λ.
(1) An Eigenvector is a vector that maintains its direction after undergoing a linear transformation.
(2) An Eigenvalue is the scalar value that the eigenvector wasmultiplied by during the linear transformation.

lets take an example :-

Here A is our Matrix and x is vector





 lets take another example :-