用于开发税务票据管理的软件

				procedure MIDPNT(A, B:real;var S:real; N:integer);
				var
				    TNM,DEL,DDEL,X,SUM:real;
				    J,IT:integer;
				begin
				    If N = 1 Then
				    begin
				        S:=(B - A) * FUNC(0.5 * (A + B));
				        IT:=1;
				    end
				    Else
				    begin
				        IT:=Trunc(Exp((N - 2)*Ln(3)));
				        TNM:=IT;
				        DEL:=(B - A) / (3 * TNM);
				        DDEL:=DEL + DEL;
				        X:=A + 0.5 * DEL;
				        Sum:=0;
				        For J:=1 To IT do
				        begin
				            Sum:=Sum + FUNC(X);
				            X:=X + DDEL;
				            Sum:=Sum + FUNC(X);
				            X:=X + DEL;
				        end;
				        S:=(S + (B - A) * Sum / TNM) / 3;
				    end;
				end;