function z=HouseholderQy(A,y);
% HOUSEHOLDERQY applies Householder reflections
%   z=HouseholderQy(A,y); computes z=Qy using the Householder
%   reflections Q stored as vectors in the matrix A by
%   A=HousholderQR(A)

[m,n]=size(A); z=y;
for j=n:-1:1,
  z(j:m)=z(j:m)-A(j:m,j)*(A(j:m,j)'*z(j:m));
end;