"Klein-Gordon equation" E = sqrt(px^2 c^2 + py^2 c^2 + pz^2 c^2 + m^2 c^4) P = (E/c, px, py, pz) X = (c t, x, y, z) gmunu = ((1,0,0,0),(0,-1,0,0),(0,0,-1,0),(0,0,0,-1)) PX = dot(P,gmunu,X) psi = A exp(-i/hbar PX) + B exp(i/hbar PX) D(f) = -d(f,t,t) + c^2 d(f,x,x) + c^2 d(f,y,y) + c^2 d(f,z,z) "Verify psi" check(hbar^2 D(psi) == m^2 c^4 psi) "ok" Run