Can someone explain to my why, according to many average calculators, the average of this array is some very small negative number instead of zero?
[-5.4, -4.4, -2.4, -1.4, 13.6]
for example, numpy.average and numpy.mean return this value:
-3.5527136788e-16
Because float numerics is not perfect. And simply this does not sum to 0, but to something around 1e-14 in this system. You can find even more funny things - change order of your numbers and then calculate sum/mean and you will find that result depends on ordering too. The short story is that you cannot express 0.4 nor 0.6 in base 2, which is used in computers.
