Аннотация:The Wielandt–Hoffman and J.-g. Sun theorems estimate the magnitude of perturbations inthe eigenvalues of a normal matrix caused by perturbations of its entries. In the theory of congruencetransformations, unitoid matrices and their canonical angles play, to a certain extent, the role of diagonalizable matrices and their eigenvalues. In particular, normal matrices are unitoid. This paper discusses analogs of the Wielandt–Hoffman and Sun theorems relating to canonical angles.