A method and apparatus for performing a radix-4 fast Hadamard transform (FHT) with reduced complexity and for directly determining the maximum output of a fast Hadamard transform using either a radix-4 transform or radix-2 transform without actually generating the outputs. The radix-4 fast Hadamard transform...http://www.google.com/patents/US7003536?utm_source=gb-gplus-sharePatent US7003536 - Reduced complexity fast hadamard transform
