get_distribution() has a problem about the negative weight value

[haithink]

if (fabs(cur_range) <= w && w < fabs(cur_range * 2))

if w is negative, then this condition would never be satisfied, so I think this line of code should be change to
if (fabs(cur_range) <= fabs(w) && fabs(w) < fabs(cur_range * 2))