UserForm1的程式 Const period As Integer = 4 Const maxerror As Double = 0.00000001 Dim payment(period) As Double '廣域變數 4 維度的陣列 Private Sub CommandButton1_Click() Dim a, b, c, f, gap As Double Dim loopNumber As Integer a = 0 b = 1 gap = 10 loopNumber = 10 payment(0) = TextBox1.Value payment(1) = TextBox2.Value payment(2) = TextBox3.Value payment(3) = TextBox4.Value f = npv(a) If f = 0 Then Label9.Caption = 0 ElseIf f < 0 Then Label9.Caption = "內部報酬率小於 0." Else Do While gap > mexerror And Abs(f) > maxerror And loopNumber < 300 loopNumber = loopNumber + 1 c = (a + b) / 2 f = npv(c) If Abs(f) > maxerror And gap > maxerror Then If f > 0 Then ...