reshape函数
reshape(X,M,N) or reshape(X,[M,N]) returns the M-by-N matrix whose elements are taken columnwise from X. An error results if X does not have M*N elements.
a = 0:2:11; % [0 2 4 6 8 10]
b = reshape(a,2,3); % [0 4 8
% 2 6 10]
c = [1 2;3 4];
d = reshape(c,4,1); % [1
% 2
% 3
% 4]
randperm函数
randperm Random permutation.
P = randperm(N) returns a vector containing a random permutation of the integers 1:N. For example, randperm(6) might be [2 4 5 6 1 3].
P = randperm(N,K) returns a row vector containing K unique integers selected randomly from 1:N. For example, randperm(6,3) might be [4 2 5].