"Verify crossing symmetry" M1 = (s^2 + u^2) / t^2 + 2 u^2 / (s t) + (t^2 + u^2) / s^2 M2 = (s^2 + u^2) / t^2 + 2 s^2 / (t u) + (s^2 + t^2) / u^2 X1 = eval(M1, s,S, u,s, S,u) X2 = eval(M2, s,S, u,s, S,u) check(M1 == X2) check(M2 == X1) "ok" Run