Matrix from an array

Let say A=1:15 is an array. How to obtain a matrix such that

B = [1 2 3 4 5 6; 4 5 6 7 8 9; 7 8 9 10 11 12; 10 11 12 13 14 15] ; %last n=3 elements of previous row repeats

[Ankit]

You need to create a loop in case you want to do it repeated number of times

A=1:15;
B = [A(1:6);A(4:9);A(7:12);A(10:15)];

Answer 1

[Andrei Bobrov]

A=1:15;
n = 6;
k = 3;

m = numel(A);
B = A((1:k:m - n + 1)' + (0:n-1));
% for old MATLAB < R2016a
B = A(bsxfun(@plus,(1:k:m - n + 1)', (0:n-1)));

[brijesh soni]

Many thanks !

Answer 2

[Bob Thompson]

Not sure how to do it without a loop or just defining the indices, but here's something simple.

A = 1:15;
for i = 1:length(A)/3-1
    B(i,:) = A((i-1)*3:(i+1)*3);
end