Thanks everyone for your help. The problem is that the argument changed in the function, a new feature for Fortran, but it gives me much troble. Ming ******************************* * Department of Mathematics * * University of S. Florida * * 4202 E. Fowler Ave, Phy 114 * * Tampa, FL, 33620 * * (813)-974-2537(O) * ******************************* ================================================================= Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =================================================================