PROGRAM d12r7(input,output);
(* driver for routine CORREL *)
CONST
   n=64;
   n2=128;      (* n2=2*nn *)
   pi=3.1415927;
TYPE
   glnarray = ARRAY [1..n] OF real;
   gl2narray = ARRAY [1..n2] OF real;
   gldarray = gl2narray;
VAR
   i,j : integer;
   cmp : real;
   data1,data2 : glnarray;
   ans : gl2narray;

(*$I MODFILE.PAS *)
(*$I FOUR1.PAS *)

(*$I TWOFFT.PAS *)

(*$I REALFT.PAS *)

(*$I CORREL.PAS *)

BEGIN
   FOR i := 1 to n DO BEGIN
      data1[i] := 0.0;
      IF ((i > ((n DIV 2)-(n DIV 8))) AND 
         (i < ((n DIV 2)+(n DIV 8)))) THEN
         data1[i] := 1.0;
      data2[i] := data1[i]
   END;
   correl(data1,data2,n,ans);
(* calculate directly *)
   writeln ('n':3,'CORREL':14,'direct calc.':18);
   FOR i := 0 to 16 DO BEGIN
      cmp := 0.0;
      FOR j := 1 to n DO BEGIN
         cmp := cmp+data1[((i+j-1) MOD n)+1]*data2[j]
      END;
      writeln (i:3,ans[i+1]:15:6,cmp:15:6)
   END
END.