Naturally ordered Hadamard matrix permuted into sequency-ordered Hadamard matrix. The number of sign changes per row in the naturally ordered matrix is (0, 15, 7, 8, 3, 12, 4, 11, 1, 14, 6, 9, 2, 13, 5, 10), in the sequency-ordered matrix the number of sign changes is consecutive.
Binary Walsh matrix as a matrix product. The binary matrix (white 0, red 1) is the result with operations in F2. The gray numbers show the result with operations in R.
In mathematics, a Walsh matrix is a specific square matrix of dimensions , where are some particular natural number. The entires of the matrix are either +1 or -1 and its rows as well as columns are orthogonal, i.e. dot product is zero. The Walsh matrix was proposed by Joseph L. Walsh in 1923. Each row of a Walsh matrix corresponds to a Walsh function.
The naturally orderedHadamard matrix is defined by the recursive formula below, and the sequency-ordered Hadamard matrix is formed by rearranging the rows so that the number of sign changes in a row is in increasing order. Confusingly, different sources refer to either matrix as the Walsh matrix.
The Walsh matrix (and Walsh functions) are used in computing the Walsh transform and have applications in the efficient implementation of certain signal processing operations.