Log Function

[kvarnerexpress 0]

Hi all.

I have some prob with log function.
The code below is not working, it returns a false value.
The value is not same with what I calculate using scientific calculator.

Using my program:
N=2
Na=1
log(N/Na)=0.6931

Using scientific calculator:
N=2
Na=1
log(N/Na)=0.30102999566

Code:

Na = 0temp = 0temp1 = 0rs.MoveFirstDo    For column = 1 To rs.Fields.Count - 1        'If rs.Fields(column) <> Null Then        If Not IsNull(rs.Fields(column).Value) Then            Na = Na + 1        End If    Next column    N = rs.Fields.Count - 1    temp = Log(N / Na)    temp1 = Format(temp, "0.0000")    rs2.AddNew    rs2!Na = temp1    rs2.UpdateNa = 0rs.MoveNextLoop Until rs.EOF

kvarnerexpress

[Galahad 0]

Yes, I had that same problem once...
In Visual Basic, LOG function is returning a value of natural logarithm (base2), whereas in math LOG specifies Base10 logarithm (or at least I think so). Now, in scientific calculator, you might have noticed LN button, just above the LOG button. If you do that function, you will get the value you want. So, in order to get the numbers you need, use this code or put it in a function:

Public Function MyLog(ByVal Number As Double) As Double  MyLog = Log(Number) / Log(10)End Function

This should give you the values you need, so your code might look something like this:

Na = 0temp = 0temp1 = 0rs.MoveFirstDo   For column = 1 To rs.Fields.Count - 1       'If rs.Fields(column) <> Null Then       If Not IsNull(rs.Fields(column).Value) Then           Na = Na + 1       End If   Next column   N = rs.Fields.Count - 1   temp = Log(N / Na) / Log(10)   temp1 = Format(temp, "0.0000")   rs2.AddNew   rs2!Na = temp1   rs2.UpdateNa = 0rs.MoveNextLoop Until rs.EOF

[dul 0]

Hi. It is must be a same result. Because mathemathics didn't change. Check your code.