anchor.diff:          x(i) = xi
           y(i) = yi
           z(i) = zi
  +        c = 1000
         end if
         c = c + 1
         !read *, dum
  
positive.code:         x(i) = xi
          y(i) = yi
          z(i) = zi
        end if
        c = c + 1
        !read *, dum
  
negative.code:         x(i) = xi
          y(i) = yi
          z(i) = zi
          c = 1000
        end if
        !print *, x(i),y(i),z(i)
        !print *, F
  