anchor.diff:  c
   c----------------------------------------------------------------------
   c
  +        subroutine synchronize_rbForce ( )
  +c
  +        use rigidBodyFlag
  +        use rigidBodyForce
  +        use core_rigid_body
  +c
  +        include "common.h"
  +c
  +        real*8, dimension(numrbs) :: ax, ay, az, px, py, pz, ag, sc
  +c
  +c.... XXX need to add rotation motion here
  +        do j = 1,numrbs
  +          if (rbsMM(j) .ne. 1)
  +     &      call error('rigidBodyBCElas','not support mode',rbsMM(j))
  +        enddo
  +c
  +        ax = 1.0
  +        ay = 0.0
  +        az = 0.0
  +        px = 0.0
  +        py = 0.0
  +        pz = 0.0
  +        ag = 0.0
  +        sc = 0.0
  +c
  +        call core_update_rbms(rbTotalDisp(:,1),
  +     &                        rbTotalDisp(:,2),
  +     &                        rbTotalDisp(:,3),
  +     &                        ax, ay, az,
  +     &                        px, py, pz,
  +     &                        ag, sc,
  +     &                        rbsTags(:), numrbs)
  +c
  +        return
  +        end
  +c
  +c
  +c----------------------------------------------------------------------
  +c
   
   c
   c----------------------------------------------------------------------
   c
   
  -c
  -c----------------------------------------------------------------------
  -c
  -
  
positive.code:         rbTorque = 0.0
  c
          rbDisp = 0.0
          rbForceOld = 0.0
          rbTorqueOld = 0.0
          rbVelOld = 0.0
  
negative.code:         deallocate( rbTorque )
  c
          deallocate( rbDisp )
          deallocate( rbTotalDisp )
          deallocate( rbForceOld )
          deallocate( rbTorqueOld )
          deallocate( rbVelOld )
  