Random Path Pick

   dimension xlat(20),xlon(20),id(20),ip(5)
               r = 6378
               call random_seed
               call random_number(r1)
               call random_number(r2)
               ib = floor(60*r2)
               do i = 1,60
               read(21,*)i1,i2,i3,i4,i5
                if (i.eq.ib) then
                    write(*,*)ib,i1,i2,i3,i4,i5
                    write(*,*)
               ip(1) =i1
               ip(2) =i2
               ip(3) =i3
               ip(4) =i4
               ip(5) =i5
                end if
               end do
               do i  = 1,5
               read(1,*)ix,x1,x2
               id(i) = ix
               xlat(i) = x1/57.1
               xlon(i) = x2/57.1
               end do
               do i = 1,4
           dlat = xlat(ip(i)) - xlat(ip(i+1))
           dlon = xlon(ip(i)) - xlon(ip(I+1))
        a=(sin(dlat/2))**2+cos(xlat(ip(i)))*cos(xlat(ip(i+1)))*(sin(dlon/2))**2 
           b = sqrt(a)
           c = 2 * asin(b)
           d= r*c
           d0 = d+d0
              write(*,*)ip(i),ip(i+1), d,d0
            end do
                stop
                 end