m; % this is your 432x90 matrix
N = 15; % number of small matrices
res(N).small_matrix = []; % init empty nonscalar struct array for results
cols = 1:size(m, 2);
for n = 1:N
res(n).small_matrix = m(:, mod(cols, N) == mod(n, N));
end
This may not be the best solution though, it is not clear why you need to 'cut up' the initial matrix to smaller ones. If it is about just accessing certain parts of the data, it may not be such a good idea to do the whole thing, but you could access the part you need at any given time using this piece:
m(:, mod(cols, N) == mod(n, N))
