********>Bugfix 12:
Author: Dave Case (reported by Dat Nguyen)
Date: 06/15/2004

Programs: sander

Description: When extra points are present, their masses are irrelevant, and
             are set to zero in the fix_masses() routine in extra_pts.f.
             However, before this happens, an inverse mass is calculated in
             rdparm2().  This can lead to a crash for some machines if the
             input mass is zero.

Fix:  Apply the following patch to $AMBERHOME/src/sander/rdparm.f

------------------------------------------------------------------------------
*** rdparm.f	2004/03/14 06:23:51	8.0
--- rdparm.f	2004/06/15 20:47:00
***************
*** 812,818 ****
           
           !         -- make inverse in "old" Lwinv area
           
!          x(k) = 1.0d0 / x(k)
        end do
        tmass = tmass + x(j)
     end do
--- 812,818 ----
           
           !         -- make inverse in "old" Lwinv area
           
!          if( x(k) /= 0.d0 ) x(k) = 1.0d0 / x(k)
        end do
        tmass = tmass + x(j)
     end do
------------------------------------------------------------------------------

Temporary workarounds: none that make more sense than applying the patch