% assembles HELLO matrix
%   see Trefethen&Bau lecture 9, exer

bl = ones(8,6);
H = bl;
H(1:3,3:4) = zeros(3,2);
H(6:8,3:4) = zeros(3,2);
E = bl;
E(3,3:6)   = zeros(1,4); 
E(6,3:6)   = zeros(1,4); 
L = bl;
L(1:6,3:6) = zeros(6,4);
O = bl;
O(3:6,3:4) = zeros(4,2);

HELLO = zeros(15,40);
HELLO(2:9,2:7)    = H;
HELLO(3:10,10:15) = E;
HELLO(4:11,18:23) = L;
HELLO(5:12,26:31) = L;
HELLO(6:13,34:39) = O;

spy(HELLO)