How to calculate eigenvalues in Octave and Matlab

To calculate the eigenvalues of a square matrix in Matlab and Octave, use eig() function

eig(x)

The parameter x is a square matrix.

The eig() function finds the eigenvalues of the matrix.

Example

Create a 3x3 square matrix

>> M=[1 2 1 ; 0 1 2 ; 1 2 0 ]
M =

1 2 1
0 1 2
1 2 0

Calculate the eigenvalues of the matrix using the eig(M) function

>> eig(M)
ans =

-1.39138
0.22713
3.16425

The function outputs the eigenvalues.

These are the solutions to the characteristic equation of the matrix.