PROCEDURE chebpc(c: glcarray;VAR d: glcarray; n: integer);
(* Programs using routine CHEBPC must define the type
glcarray as in routine CHEBFT. *)
VAR
   k,j: integer;
   sv: real;
   dd: glcarray;
BEGIN
   FOR j := 1 TO n DO BEGIN
      d[j] := 0.0;
      dd[j] := 0.0
   END;
   d[1] := c[n];
   FOR j := n-1 DOWNTO 2 DO BEGIN
      FOR k := n-j+1 DOWNTO 2 DO BEGIN
         sv := d[k];
         d[k] := 2.0*d[k-1]-dd[k];
         dd[k] := sv
      END;
      sv := d[1];
      d[1] := -dd[1]+c[j];
      dd[1] := sv
   END;
   FOR j := n DOWNTO 2 DO BEGIN
      d[j] := d[j-1]-dd[j]
   END;
   d[1] := -dd[1]+0.5*c[1]
END;