How to create mean matrix in multi-dimensional array

Hello,

I have multi-dimensional array that is 8x8x40. This is basically a 8x8 correlation matrix that is concatenated across 40 people. I would like to get the mean 8x8 correlation matrix for the first 20 and then the mean correlation matrix for the last 20. If I do mean(A,3) it gives me the mean for all 40 people but I would like the individual means for two groups. Would I have to divide the array into two (one for each group)? If so how would I do this?

Thanks.

Answer 1

[Azzi Abdelmalek]

a=rand(8,8,40) %example
a1=a(:,:,1:20);
a2=a(:,:,21:end)
m1=mean(a1,3)
m2=mean(a2,3)