  We give canonical matrices of a pair (A,B) consisting of a nondegenerate form
B and a linear operator A satisfying B(Ax,Ay)=B(x,y) on a vector space over F
in the following cases:
  (i) F is an algebraically closed field of characteristic different from 2 or
a real closed field, and B is symmetric or skew-symmetric;
  (ii) F is an algebraically closed field or the skew field of quaternions over
a real closed field, and B is Hermitian or skew-Hermitian with respect to any
nonidentity involution on F.
  We use a method that admits to reduce the problem of classifying an arbitrary
system of forms and linear mappings to the problem of classifying
representations of some quiver. This method was described in [V.V. Sergeichuk,
Math. USSR-Izv. 31 (1988) 481-501].
