用于开发税务票据管理的软件

				unit Unit2;
				
				interface
				uses
				    unit1;
				procedure TRAPZD(A, B:real;var S:real; N:integer);
				
				implementation
				procedure TRAPZD(A, B:real;var S:real; N:integer);
				var
				    J,IT:integer;
				    TNM,DEL,X,SUM:real;
				begin
				    If N = 1 Then
				    begin
				        S:=0.5 * (B - A) * (FUNC(A) + FUNC(B));
				        IT:=1;
				    end
				    Else
				    begin
				        IT:=Trunc(exp((N - 2)*Ln(2)));
				        TNM:=IT;
				        DEL:=(B - A) / TNM;
				        X:=A + 0.5 * DEL;
				        Sum:=0;
				        For J:=1 To IT do
				        begin
				            Sum:=Sum + FUNC(X);
				            X:=X + DEL;
				        end;
				        S:=0.5 * (S + (B - A) * Sum / TNM);
				    end;
				end;
				end.