log2 in python math module

Question

why doesn\'t it exist?

import math
[x for x in dir(math) if \'log\' in x]
>>> [\'log\', \'log10\', \'log1p\']

I know I can do log(x,2)

Answer 1

I'm not sure that there is that you want, but:

-- From math point of view you can do for example math.log(x)/math.log(2).

-- If input X has an integral type and you are waiting for the integral rounded result - you can do it rather faster with right shifting. This works with SHR command and without Taylor series + local interpolation, which is under the hood of libc log() calls.