计算债券凸性的VBA 代码

liruoyan18

代码：Function secondDur(restTime, couponRate, YTM, frequency)
    If frequency <= 1 Then
         For t = (restTime - Int(restTime)) To restTime
        If t < restTime Then
            secondDur = couponRate * t * 100 * (t + 1) _
                 / (1 + YTM) ^ (t + 2) + secondDur
        Else
            secondDur = (couponRate + 1) * 100 * t * (t + 1) _
                 / (1 + YTM) ^ (t + 2) + secondDur
        End If
       
        secondDur = secondDur
    Next t
    Else
          For t = (restTime * frequency - Int(restTime * frequency)) To (restTime * frequency)
           If t < (restTime * frequency) Then
              secondDur = couponRate / frequency * t * 100 * (t + 1) _
                    / (1 + YTM / frequency) ^ (t + 2) + secondDur
    Else
            secondDur = (couponRate / frequency + 1) * 100 * t * (t + 1) _
                 / (1 + YTM / frequency) ^ (t + 2) + secondDur
        End If
       
        secondDur = secondDur / frequency ^ 2
    Next t
    End If
  End Function
  
 
凸性=secondDur/bondprice，请问高手我上面的程序有什么问题？