How to became my Tridiagonal matrix

B=[
    16,   2  ,   3,    13;...
     5 ,  11,  10,     8;...
     9 ,   7 ,   6,    12;...
     4,  14,  15,    1]

How to became my Tridiagonal matrix

16	0	0	0
5	2	0	0
9	11	3	0
4	7	10	13
0	14	6	8
0	0	15	12
0	0	0	1

[Dana]

If you want help. you should provide a much more detailed question. I have no idea what you're asking here.

Answer 1

[Walter Roberson]

full(spdiags(B',0:-1:-3,7,4))

Answer 2

[KSSV]

Read about diag.

iwant = diag(1:5)+diag(1:4,-1)+diag(1:4,1) ;

Answer 3

[madhan ravi]

 [m, n] = size(B);
  ix = (1 : 2*m : n*2*m) + (0 : n - 1).';
 Wanted = zeros(2*m - 1 , n);
 Wanted(ix) = B