Const period As Integer = 4
Const maxerror As Double = 0.0000001
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 < 100
loopNumber = loopNumber + 1
c = (a + b) / 2
f = npv(c)
If Abs(f) > maxerror And gap > maxerror Then
If f > 0 Then
a = c
Else
b = c
gap = b - a
End If
Else
Label9.Caption = c
End If
Loop
End If
Label10.Caption = f
Label11.Caption = loopNumber
'以下是將結果輸出到WORD文件
Selection.TypeText ("躉繳:" & TextBox1.Value & "第 1 期:" & TextBox2.Value & "第 2 期:" & TextBox3.Value & "第 3 期:" & TextBox4.Value & "第 4 期:")
Selection.TypeParagraph
Selection.TypeText ("內部報酬率:" & c)
Selection.TypeParagraph
Selection.TypeText ("淨現值:" & f)
Selection.TypeParagraph
Selection.TypeText ("迴圈次數:" & loopNumber)
Selection.TypeParagraph
End Sub
Private Sub CommandButton2_Click()
End
End Sub
Function npv(rate) '計算特定折現率rate的淨現值
Dim y As Double
Dim j As Integer
y = -payment(0)
For j = 1 To period
y = y + payment(j) / (1 + rate) ^ j
Next
npv = y
End Function
