LOGn calculates the log, base n, of a specified variable or expression. 

SYNTAX:

LOGn(Cx or Exp)
where :
Cx is a conditional variable x
Exp is a Expression
n specifies the logorithmic base to use when calculating

NOTES:

The base (n) of the log CAN NOT be 1 or 0. 
See LOG Function for the natural log (equivalent to the LN Excel function)
LOG10 Math Toolbox is equivalent to the LOG Excel Function

EXAMPLES:

V95 = LOG2(V70)

Variable 95 will contain the log base 2 of variable 70: