"Verify solution (1)" psi = exp(-i / hbar (E t - px x - py y - pz z)) E = sqrt(px^2 c^2 + py^2 c^2 + pz^2 c^2 + m^2 c^4) D(f) = d(f,t,t) / c^2 - d(f,x,x) - d(f,y,y) - d(f,z,z) check(D(psi) == -m^2 c^2 / hbar^2 psi) "ok" Run