% Daubechies' filters of length 4
d4h=[1+sqrt(3),3+sqrt(3), 3-sqrt(3), 1-sqrt(3)]/sqrt(32)
d4g=d4h(4:-1:1).*[1,-1,1,-1]  % conjugate filter

% Check orthogonality
d4g*d4h'   % must be zero
d4h*d4h'   % must be 1
d4g*d4g'   % must be 1
