adding rows and storing into a matrix

Hello,

I have a matrix M of size 2880x501 containing 2880 rows. I want to select the first eight rows and all columns [that is, (1:8,:) ], add them and store the resulting row vector(1x501) in a variable 'out'. Then select the next 8 rows, add them and store the resulting row vector(again 1x501) into above variable 'out' and so on....

Finally, I shall have 360 combinations (of 8 rows each) and all these values should be stored in a single variable as

out(360x501)

Please help me achieve this.

[Andrei Bobrov]

out = squeeze(sum(reshape(M.',size(M,2),8,[]),2)).'

[zozo]

thank you @andrei

Answer 1

[Michael]

This may be possible without a loop but I don't have the knowledge, however you can loop over i:

for i = 1:360;
    out(i,:) = sum(M((i-1)*8+1 : i*8, :));
end

sum automatically operates on the matrix M(1:8,:) and returns the 1x501 vector of sums down the columns.