An eigenvalue of a square matrix A is a scalar λ for which there exists a nonzero vector v with the property that Av = λv. The eigenvalues of a real square matrix may be all real, both real and complex, or all complex. All n-by-n triangular real matrices have n real eigenvalues...
The eigenvalue and eigenvector calculator finds the eigenvalues and eigenvectors for a 2x2 or 3x3 matrix.