anchor.diff:  
   C----------------------------------------------------------------------C
   
  -      SUBROUTINE damping(A,b,nobs,nflt,damp)
  -C----
  -C Minimize length of solution to Ax = b with weighting factor damp.
  -C m=nobs n=nflt d=damp
  -C         [ A11 A12 ... A1n ]
  -C     A = [ A21 A22 ... A2n ]
  -C         [  :           :  ]
  -C         [ Am1 Am2 ... Amn ]
  -C
  -C         [ d*d  0  ...  0  ]
  -C  Append [  0  d*d ...  0  ]
  -C         [                 ]
  -C         [  0   0  ... d*d ]
  -C----
  -      IMPLICIT none
  -      REAL*8 damp
  +      SUBROUTINE green2d(A,b,obs,flt,nobs,nflt)
  +C----
  +C Create Green's functions for 2-D case and load model matrix
  +C----
  +      IMPLICIT none
         INTEGER OBSMAX,PARMAX
         PARAMETER (OBSMAX=10000,PARMAX=100)
  -      REAL*8 A(OBSMAX,PARMAX),b(OBSMAX,1)
  -      INTEGER i,j,nobs,nflt
  -      if (damp.le.0.0d0) return
  -      do 101 i = 1,nflt
  -          b(nobs+i,1) = 0.0d0
  -          do 102 j = 1,nflt
  -              if (i.eq.j) then
  -                  A(nobs+i,j) = damp*damp*1.0d0
  -              else
  -                  A(nobs+i,j) = 0.0d0
  -              endif
  -  102     continue
  -  101 continue
  -      nobs = nobs + nflt
  -      RETURN
  -      END
  -
  -C----------------------------------------------------------------------C
  -
  -      SUBROUTINE green2d(A,b,obs,flt,nobs,nflt)
  -C----
  -C Create Green's functions for 2-D case and load model matrix
  -C----
  -      IMPLICIT none
  -      INTEGER OBSMAX,PARMAX
  -      PARAMETER (OBSMAX=10000,PARMAX=100)
  -      REAL*8 flt(PARMAX,8),obs(OBSMAX,6),A(OBSMAX,PARMAX),b(OBSMAX,1)
  +      REAL*8 flt(PARMAX,7),obs(OBSMAX,6),A(OBSMAX,PARMAX),b(OBSMAX,1)
         INTEGER i,j,nobs,nflt
         REAL*8 vp,vs,dens
         REAL*8 xflt,yflt,zflt,xobs,yobs,zobs,dx,dy
  
positive.code:      1 '                       3-D: x(m) y(m) z(m) str(deg) dip(deg) ',
       2                         'wid(m) len(m)'
        write(*,*)
       1 '-smooth CONST FILE Smooth model, with weight CONST, linking ',
       2                         'file FILE (format below)'
        write(*,*)
  
negative.code:           write(*,*)
        endif
        write(*,*)
       1 'Usage: fltinv -obs OBSFILE -flt FLTFILE -2|-3 ',
       2         '[-LQR|SVD] [-smooth SMOOTH] [-smoof SMOOTHFILE] ',
       3         '[-damp DAMP] [-h]'
        write(*,*)
  