anchor.diff:                dist = dsqrt(delx*delx + dely*dely)
                 az = datan2(delx,dely)
             endif
  +C x points along strike, y points horizontal, up-dip
             x = dist*( dcos(az-d2r*str(f)))
             y = dist*(-dsin(az-d2r*str(f)))
             if (flttyp.eq.0) then
  
positive.code:       write(*,*)
       1 '-xy                     Treat geographic ',
       2                               'coordinates as ',
       2                          'Cartesian x-y (km)'
        if (str.eq.'long') then
            write(*,*)
            write(*,*)
       1 '    Geographic coordinates evlo, evla, stlo, and stla are ',
       2      'converted to x-y (in km)'
            write(*,*)
       1 '    evlo -> evx; evla -> evy; stlo -> stx; stla -> sty'
            write(*,*)
       1 '    All other input formats and units are unchanged'
            write(*,*)
       1 '    NB: strike angle still defined from N=y-direction'
            write(*,*)
            write(*,9999)
            write(*,*)
  
negative.code: C----
  C Read shear dislocations from fault file in format:
  C   evlo evla evdp(km) str dip rak slip(m) dip_wid(km) str_len(km)
  C All units are converted to SI, angles are in degrees.
  C----
        IMPLICIT NONE
        CHARACTER*40 fltf
  