x=[x1(:,:) x1(:,:)] ?

help me please if you have know how about x=[x1(:,:) x1(:,:)] ? what is doing it?

Answer 1

[Andrei Bobrov]

>> x1 =[ 1 2
      3 4];
x = [x1(:,:), x1(:,:)]
x =
     1     2     1     2
     3     4     3     4

[Gebreabzgi Pawlos]

thank you Andrei Bobrov i got your idea but since i am new to matlab i am not clear if it is specified with specified with specific points like X1 = [X1(:,P/2+1:P) X1(:,1:P/2)] if u can try to explain with example