FUNCTION VOID CalcShad(task,
           sol_dir,sol_elev,
           Coord_Surface,
           N_Shades, N_Points,
           Coord_Shades, Transp_Shades,
           Transp_Result, Three, Four)

  LANGUAGE F77

  INPUT 
     INT   task, N_Shades, N_Points, Three, Four;
     FLOAT sol_dir, sol_elev, Coord_Surface[Three,Four],
           Coord_Shades[Three,N_Points], Transp_Shades[N_Shades];

  OUTPUT
     FLOAT Transp_Result;

  EXTERNAL CalcShad(task,
           sol_dir,sol_elev,
           Coord_Surface,
           N_Shades, N_Points,
           Coord_Shades, Transp_Shades,
           Transp_Result, Three, Four)
  END_FUNCTION