A matrix is a diagonal matrix if and only if all of its non-zero values exist along the diagonal.

  • Each non-zero column of a diagonal matrix corresponds to a linearly independent basis vector.
  • The values along the diagonal are eigenvalues of the matrix.
  • The determinant of a diagonal matrix is the product of its diagonal terms.
    • Which implies that any diagonal matrix with at least one zero on the diagonal is singular.
  • Every real-valued diagonal matrix is symmetric.