用于开发税务票据管理的软件

				Procedure CORREL(DATA1,DATA2:array of real;N:integer;var ANS:array of real);
				var
				    FFT:array[0..128] of real;
				    NO2,I:integer;  DUM,DUM1,DUM2:real;
				begin
				    TWOFFT(DATA1, DATA2, FFT, ANS, N);
				    NO2:=N div 2;
				    For I:=1 To NO2 + 1 do
				    begin
				      DUM:=ANS[2 * I - 1];
				      DUM1:=FFT[2 * I - 1] * DUM + FFT[2 * I] * ANS[2 * I];
				      ANS[2 * I - 1]:=DUM1 / NO2;
				      DUM2:=FFT[2 * I] * DUM - FFT[2 * I - 1] * ANS[2 * I];
				      ANS[2 * I]:=DUM2 / NO2;
				    end;
				    ANS[2]:=ANS[N + 1];
				    REALFT(ANS, NO2, -1);
				end;