VB 处理对数Log()问题

两个有用的函数,使用时直接调用

1. 求以10为底的对数值的函数,如下:

   Private Function LogTen(X As Double) As Double
        
         '* 检验真数数有效性
         If X <= 0 Then
            MsgBox "真数的取值范围:真数>0.", vbInformation, "参数错误"
         End If
         '* 计算并返回对数值
         LogTen = Log(X) / Log(10)

   End Function

2. 求以任意数为底的对数值的函数,如下:

  Private Function LogNtr(X As Double, n As Double) As Double
        
         '* 检验底数数有效性
         If n <= 0 Or n = 1 Then
            MsgBox "底数的取值范围:底数>0 且<>1.", vbInformation, "参数错误"
         End If
         '* 检验真数数有效性
         If X <= 0 Then
            MsgBox "真数的取值范围:真数>0.", vbInformation, "参数错误"
         End If
         '* 计算并返回对数值
         LogNtr = Log(X) / Log(n)   '>  计算LognX的值

   End Function

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