Calculate the integer logarithm for an arbitrary base. The base must be greater than 1, the second argument, the number whose logarithm is sought, should be positive, otherwise the result is meaningless.
base ^ integerLogBase# base m <= m < base ^ (integerLogBase# base m + 1)
base > 1 and
m > 0.
Calculate the integer base 2 logarithm of an
The calculation is more efficient than for the general case,
on platforms with 32- or 64-bit words much more efficient.
The argument must be strictly positive, that condition is not checked.