Chapter 5: Eigenvalues and Eigenvectors
Let A be an n×n matrix over ℂ. The complex number λ is called an eigenvalue of A if and only if the matrix (A − λIn) is singular. Let x be a nonzero column vector in ℂn. Then x is called an eigenvector belonging to (or associated with) the eigenvalue λ if and only if (A − λIn)x = 0. The equation