anchor.diff:        lon2 = lon1 + datan2(dsin(az)*dsin(dist)*dcos(lat1),
        1                           dcos(dist)-dsin(lat1)*dsin(lat2))
   
  -C     Return azimuth, latitude, and longitude in degrees
  +C     Return input values in initial units
  +      dist = dist*6371.0d0
         az = az*r2d
         lat1 = lat1*r2d
         lon1 = lon1*r2d
  +      
   
         RETURN
         END
  
positive.code:       END
  
  c----------------------------------------------------------------------c
  
  
  
negative.code:       IMPLICIT none
        REAL*8 pi,r2d,d2r
        PARAMETER (pi=4.0d0*datan(1.0d0),r2d=1.8d2/pi,d2r=pi/1.8d2)
        REAL*8 lon1,lat1,lon2,lat2,colat1,colat2,dlon,dlat,a
        REAL*8 dist,az
  C----
  C Check if points are polar opposite
  