I find that frequently I have the cumbersome double ptot = Math.sqrt(t.getMomentumX()*t.getMomentumX() + t.getMomentumY()*t.getMomentumY() + t.getMomentumZ()*t.getMomentumZ()); at several places throughout my code (I see in many other peoples also). Since ptot is used so frequently doesn't make sense to have it as a method in the particle and track classes? (Sorry if this is an old and discarded issue). I don't have a strong opinion on the method name. Bob -- Robert J. Wilson Professor of Physics Department of Physics Colorado State University Fort Collins, CO 80523 Phone: (970) 491 5033 Fax: (970) 491 7947 Email: [log in to unmask] August 2000 - July 2001: ======================== Institut de Fisica d'Altes Energies Universitat Autonoma de Barcelona E-08193 Bellaterra (Barcelona) SPAIN Phone: (011 34) 93 581.33.22 Fax: (011 34) 93 581.19.38 Email: [log in to unmask] ========================