X(f) = x f P(f) = -i hbar d(f,x) X(P(psi(x,t))) - P(X(psi(x,t))) X2(f) = X(X(f)) P2(f) = P(P(f)) A = X2(P2(psi(x,t))) - P2(X2(psi(x,t))) B = 2 i hbar (X(P(psi(x,t))) + P(X(psi(x,t)))) check(A == B) "ok" Run