INTERFACE SPHomoLabel;

(* Label-to-index mapping for homogeneous coefficients *)

TYPE 
  T = ARRAY[0..2] OF CARDINAL;
    (* 
      Standard label of a Bezier Control value or
      coefficient of a homogeneous polynomial, 
      eg. (6,0,0) or (3,2,1)

      The term order is given by the algorithm
        poly := 0; 
        index := 0;
        FOR i := 0 TO d DO
          FOR j := 0 TO d-m DO
            k := d - m - n;
            poly := poly + c[index] * B^d_{i,j,k};
            index := index + 1;
          END
        END;
    *)

PROCEDURE IndexToLabel(i: CARDINAL; d: CARDINAL): T;

PROCEDURE LabelToIndex(e: T; d: CARDINAL): CARDINAL;
  (* 
    Maps standard labels to position in the ControlValue array; e.q. 
     (6,0,0) <--> 0, (5,1,0) <--> 1, ... , (0,0,6) <--> 27 *)

END SPHomoLabel.