A Hadamard matrix is an orthogonal matrix whose entires are all either 1 or − 1. For example is a Hadamard matrix of order 2. True to Stigler’s law of eponymy, James Joseph Sylvester investigated Hadamard matrices before Jacques Hadamard. Sylvester saw how to bootstrap the example above into more examples. If H is a […] The post Constructing Hadamard matrices first appeared on John D. Cook .