Giải:
>> X = [ 1 2 3; 4 5 6; 7 8 9]
X =
1 2 3 4 5 6 7 8 9
>> mean(X,1)
ans =
4 5 6
>> mean(X,2)
ans =
2 5 8
>> mean(X,'all')
ans =
5
>> mean(X,[2 1])
ans =
5