anchor.diff:        COMMON /TAG/    thru
   
   C----
  -C Initialize components of displacement
  -C u(1-3) - strike slip sources
  -C u(4-6) - dip slip sources
  -C f(i,j) - dummy displacement variables
  -C
  +C INITIALIZE COMPONENTS OF DISPLACEMENT
  +C   U(1-3): DISPLACEMENT FROM UNIT STRIKE-SLIP SOURCE
  +C   U(4-6): DISPLACEMENT FROM UNIT DIP-SLIP SOURCE
  +C   F(I,J): DUMMY DISPLACEMENT VARIABLES
   C thru   - a tag indicating number of times through calculation;
   C          used for generating mirror source
   C----
  
positive.code: C OUTPUT: strain at receiver
  C----
        IMPLICIT NONE
        REAL*8 pi,d2r,eps
        PARAMETER (pi=4.0d0*datan(1.0d0),d2r=pi/1.8d2,eps=1.0d-4)
        REAL*8 x,y,stdp,evdp,z,c,d,p,q,ksi(2),eta(2)
        REAL*8 dipin,rakin,wid,len,slip,Mss,Mds
        REAL*8 vp,vs,dens
  
negative.code: C----
  C Source and halfspace constants
  C----
        call DIPVAR(dipin)
        call hafspc(vp,vs,dens)
        call moment1(Mss,Mds,slip,rakin)
  C----
  