如何让我的大数乘法功能更快？

Question

我最近创建了一个使用大量（如十进制数超过100位）数字的宏。为了解决这些问题，我在互联网上搜索了一些想法并优化了我发现的许多符合我要求的东西。

然而，我发现了一个有效的大量乘法函数......但在我看来并不太有效。

我试图从头开始思考自己的算法，我试图优化这个算法...但我似乎无法更快地得到它。

我试图想出一种方法，它不需要factorOneNbr来引用LargeMult ......但什么都没有。

如果有人有任何指示我会很感激。

谢谢！

以下是代码：

Public Sub Initialize()
Static Initialized As Boolean
If Initialized Then Exit Sub
Initialized = True
cDecMax = _
    CDec(Replace("79,228,162,514,264,337,593,543,950,335", ",", ""))
        'this is 2^96-1
cDecMaxLen = Len(cDecMax) - 1
cSqrDecMaxLen = cDecMaxLen \ 2
End Sub

Function Ceil(x As Single) As Long
    If x < 0 Then Ceil = Fix(x) Else Ceil = -Int(-x)
End Function

Function LargeMult(ByVal Nbr1 As String, ByVal Nbr2 As String) As String
    Initialize
    Dim negative As Boolean
    negative = False

    If Left(Nbr1, 1) = "-" And Left(Nbr2, 1) = "-" Then
        Nbr1 = Right(Nbr1, Len(Nbr1) - 1)
        Nbr2 = Right(Nbr2, Len(Nbr2) - 1)
    ElseIf Left(Nbr1, 1) = "-" Then
        Nbr1 = Right(Nbr1, Len(Nbr1) - 1)
        negative = True
    ElseIf Left(Nbr2, 1) = "-" Then
        Nbr2 = Right(Nbr2, Len(Nbr2) - 1)
        negative = True
    End If

    If Len(Nbr1) <= cSqrDecMaxLen And Len(Nbr2) <= cSqrDecMaxLen Then
        LargeMult = CStr(CDec(Nbr1) * CDec(Nbr2))
        If negative Then LargeMult = "-" & LargeMult
        Exit Function
    End If
    If Len(Nbr1) > cSqrDecMaxLen Then
        LargeMult = factorOneNbr(Nbr1, Nbr2)
    Else
        LargeMult = factorOneNbr(Nbr2, Nbr1)
    End If

    If negative Then LargeMult = "-" & LargeMult

End Function

Private Function factorOneNbr(ByVal LargeNbr As String, _
        ByVal Nbr2 As String) As String
    Dim NbrChunks As Integer, i As Integer, _
        Nbr1Part As String, PowersOf10 As Integer, _
        Rslt As String, FinalRslt As String
    FinalRslt = "0"
    NbrChunks = Ceil(Len(LargeNbr) / cSqrDecMaxLen) - 1
    For i = NbrChunks To 0 Step -1
        Nbr1Part = Mid(LargeNbr, i * cSqrDecMaxLen + 1, cSqrDecMaxLen)
        Rslt = LargeMult(Nbr1Part, Nbr2)
        FinalRslt = LargeAdd(FinalRslt, Rslt & String(PowersOf10, "0"))
        PowersOf10 = PowersOf10 + Len(Nbr1Part)
        Next i
    factorOneNbr = FinalRslt
End Function