Thanks @tom I am unsure to follow you. It is true that the paper only suggest using max/min/and odd power mean from 1 to 10.
However this does not solve the issues of having negative numbers as far I understand.
i.e. Taking the 3rd power mean of -9,-3 ( gen_mean([-9, -3],3)  try to do np.power(-378,1/3) which solution is complex).
Would you mind elaborating?
Best,