How to Sum each nth Pages of a Three Dimensional Matrix?

Hello all,

I have a matrix with the size of 21x23x246. I would like to sum all arrays of the first, second, third ... and 8th pages and then sum the ninth, 10th ... and 16th pages and so on. In other words, I would like to sum each 8th pages of the matrix.

In the end, I would have a matrix with the dimension of 21x23x31.

Thank you in advance.

Answer 1

[Fangjun Jiang]

the size of your original matrix, say A, needs to be 21x23x248, right?

sz=size(A)
B=reshape(A,sz(1),sz(2),8,[]);
squeeze(sum(B,3))

[ehsan]

Thanks for your response. Actually, the size of my original matrix is 21x23x246 and not 248. Therefore, the latest summation is among the latest 6 pages and not 8 pages.

I got this error:

Error using reshape Product of known dimensions, 3864, not divisible into total number of elements, 118818.

[Fangjun Jiang]

that is the reason I asked the question. You could append two pages of all zero matrix first.

[Fangjun Jiang]

ok, the last statement should give you the result.

C=squeeze(sum(B,3))

[ehsan]

I added two pages with zeros and it works fine.

Thanks alot.

[Simbarashe Chidzambwa]

What do sz(1) and sz(2) represent?

[Fangjun Jiang]

sz=size(A), A is a 21x23x246 matrix, so sz(1) is 21, sz(2) is 23.

[Simbarashe Chidzambwa]

Thank you Fangjun.