Algorithm which swaps the columns of a matrix A mx(n*2) without looping?

Hi all, I need an algorithm which swaps the columns of a matrix A mx(n*2) without looping in the following way:

%if A=[column 1, column 2, ... column n, column n+1, ... column n*2] 
%I want B=[column 1, column n+1, column 2, column n+2, ... column n, column 2*n]

E.g.

A=[1 2 3 4; 5 6 0 9; 1 2 1 8]
B=[1 4 2 3; 5 9 6 0; 1 8 2 1]

Could you help me?

Answer 1

[Andrei Bobrov]

i1 = reshape(1:size(A,2),[],2)';
B = A(:,i1(:));