Wait until you're done, then use the "magic" of Matlab internal storage order and rearranging...let's do a small example to show the idea--
>> x=rand(6,3) % generate small sample data set...
x =
0.7094 0.1190 0.7513
0.7547 0.4984 0.2551
0.2760 0.9597 0.5060
0.6797 0.3404 0.6991
0.6551 0.5853 0.8909
0.1626 0.2238 0.9593
>> reshape(x,3,[]) % reshape based on number to average
ans =
0.7094 0.6797 0.1190 0.3404 0.7513 0.6991
0.7547 0.6551 0.4984 0.5853 0.2551 0.8909
0.2760 0.1626 0.9597 0.2238 0.5060 0.9593
>> mean(ans) % and take the mean; Matlab works by column by default
ans =
0.5800 0.4991 0.5257 0.3832 0.5041 0.8498
>> reshape(ans,2,[]) % reshape back to three columns and voila!!!
ans =
0.5800 0.5257 0.5041
0.4991 0.3832 0.8498
>> [mean(x(1:3,:)); mean(x(4:6,:))] % check it's right...
ans =
0.5800 0.5257 0.5041
0.4991 0.3832 0.8498
>>
OK, so to do the above in general
nAvg=3;
N=length(x);
nAvgMeans=reshape(mean(reshape(x,nAvg,[])),N/nAvg,[]);
