anchor.diff:  c
         include "implicit.inc"
   c
  +c...  parameter definitions
  +c
  +      include "rconsts.inc"
  +c
   c...  subroutine arguments
   c
         double precision sdev(6),stn(6),sinv1,steff
  
positive.code: c
        intrinsic sqrt
  c
  c...  user-defined functions
  c
        double precision sprod
        external sprod
  
negative.code: c*      write(6,*) "Hello from invar_f!"
  c
        sinv1=stn(1)+stn(2)+stn(3)
        smean=sinv1/three
        sdev(1)=stn(1)-smean
        sdev(2)=stn(2)-smean
        sdev(3)=stn(3)-smean
  