program latlon
      
C*************************************************************************
C  Compute the distance in miles and kilometers between 0-0 and all other
C	unit degrees on the earth
C
C  Use arclength = arccos(cos(a1) * cos(b1) * cos(a2) * cos(b2) +
C			cos(a1) * sin(b1) * cos(a2) * sin(b2) +
C			sin(a1) * sin(a2)) * r
C 	where r is radius of earth, a1 is lat of origin, a2 is lon of origin
C		b1 is lat of endpoint, and b2 is lon of endpoint
C*************************************************************************

      real latdec, londec, latrad, lonrad, distmile, distkm
      real latsource, lonsource, deg2rad, arclength
      real lat0rad, lon0rad
      parameter(radiuskm=6378.0, radiusmile=3963.1)  
      
      latdec = 42.0
      londec = 15.0
      
      latsource = 0.0  ! SAME AS RADIANS
      lonsource = 0.0  ! SAME AS RADIANS
      
      lat0rad = deg2rad(latsource)
      lon0rad = deg2rad(lonsource)
      
      do 100 latdec = -90.0, 90.0, 1.0
         do 110 londec = 0.0, 360.0, 1.0
	 
            latrad = deg2rad(latdec)
            lonrad = deg2rad(londec)
      
            distkm = arclength(lat0rad, lon0rad, latrad, 
     +                         lonrad, radiuskm)
            distmile = arclength(lat0rad, lon0rad, latrad, 
     +                           lonrad, radiusmile)
      
            print *, latdec, londec,distkm, distmile
 110     end do
 100  end do
      
      stop
      end
C---------------------------------------------------------------------------
      function deg2rad(degree)
      
      real degree, deg2rad, pi
      parameter(pi=3.14159)
      
      deg2rad = degree * 2.0 * pi / 360.0
      
      return
      end
C--------------------------------------------------------------------------
      function arclength(a1, b1, a2, b2, r)
      
      real a1, a2, b1, b2, r
      
      arclength = acos(cos(a1) * cos(b1) * cos(a2) * cos(b2) +
     +                   cos(a1) * sin(b1) * cos(a2) * sin(b2) +
     +                   sin(a1) * sin(a2)) * r
     
      return
      end