I guess you do not understand my formula... Given z a non-zero integer, either z=2n or z=2n-1 or z=-2n or z=-(2n-1), for some natural n>0... f(n) is defined ac

I guess you do not understand my formula... Given z a non-zero integer, either z=2n or z=2n-1 or z=-2n or z=-(2n-1), for some natural n>0... f(n) is defined according to each case. Uhu? And AFAIK f(f(n))=-n. This should not be too hard to express in 32 bit arithmetic. With bitwise shifts etc.