How on Factorial

[Stefan Behnel]

Arnaud Delobelle, 28.10.2010 20:38:
> using ~-n instead of n-1 if obfuscatory and doesn't
> even save keystrokes!  (Although it could in other situations, e.g
> 2*(n-1) can be written 2*~-n, saving two brackets.)

Sure, good call. And look, it's only slightly slower than the obvious code:

$ python3 -m timeit -s "n=30" "2*~-n"
10000000 loops, best of 3: 0.0979 usec per loop

$ python3 -m timeit -s "n=30" "2*(n-1)"
10000000 loops, best of 3: 0.0841 usec per loop

Stefan