On Sun, January 31, 2010 6:05 pm, Tianhong YU wrote: > In eq(2), the "dt\prime" should be inside the bracket. Thank you. It's been fixed and applied. Brad Bradley S. Meyer Department of Physics and Astronomy Clemson University Clemson, SC 29634-0978 mbradle at clemson.edu http://nucleo.ces.clemson.edu