%% syntaxe : vect1 vect2 angle3d /angle3d { 4 dict begin normalize3d /vect2 defpoint3d normalize3d /vect1 defpoint3d /cosalpha vect1 vect2 scalprod3d def /sinalpha vect1 vect2 vectprod3d norme3d def sinalpha cosalpha atan end } def