Sequency (Walsh) ordered Hadamard matrix

generate a sequency (Walsh) ordered Hadamard matrix of size N.

Description

This function generates a sequency (Walsh) ordered Hadamard matrix of size N.

A previously submitted m file already implements this, but this is a much faster algorithm.

Acknowledgements

The author wishes to acknowledge the following in the creation of this submission:
Sequency(Walsh) ordered Hadamard matrix

• MATLAB release: MATLAB 7.6 (R2008a)

[Jos x@y.z]

This function errors for me on "bi2de", but anyways, how does this compares to the following code:

n = 4 ; % should be power of 2
H2 = [1 1 ; 1 -1] ;
H = H2 ;
for i=2:log2(n),
   H = kron(H2,H) ;
end ;

[Thomas R]

You could avoid the whole bin2dec business with

seqord = 2.^[0:(k-1)]*graycode' + 1;

[Royi Avital]

Something is strange to me.
Let's say A is 4X4 matrix.
B = fwht(fwht(A)')
C = walsh(4) * A * walsh(4) /4
The problem is B doesn't equal C.
How come?

Thanks.