math - How to calculate log of a complex number to a base other than 'e'? -

I have been deducted virtual VB6 from this project:

   
 
 
 You can use the following mathematical:  
  <10> log 10 = log (x) / log (10) log2 = log (x) / log (2) "alt text">  
 ... logon = log (x) / log (n)