MATLAB: How to average columns of matrix without loop

Question

Hi! I have a rather big (about 1 000 000 X 10 000) matrix. I want to averaging n column blockes. For example:

n = 3;
A = [1 2 3 4 5 6 7 8 9;10 4 1 2 6 4 1 -4 0];

The result shuold be:

res =
     2     5     8
     5     4     1

I know it could be done with a for loop using mean, but in my code that would be inside of other for loops, which makes a huge runtime. What I basically need is a mooving averege without overleap, but I couldn't find such matlab function. I wonder, if there is a loop free solution for this.

Answer 1

reshape(mean(reshape(A',n,[]))',size(A,2)/n,[])'