Fast 2D Walsh-Hadamard Transform

The function implement the 2D dyadic(Paley) ordered fast in-place Walsh-Hadamard transform.

The function implement the 2D dyadic(Paley) ordered fast in-place Walsh-Hadamard transform, which can be used in signal processing, pattern recognition and Genetic alogorithms. This algorithm uses a Cooley-Tukey type signal flow graph and is implemented in N log2 N
additions and subtractions. Data sequence length must be an integer power of 2. The inverse transform is the same as the forward transform except for the multiplication factor N x N.