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bbhadamard Create a black-box operator for a Hadamard matrix. BB=bbhadamard(N) creates an N-by-N Hadamard matrix. A Hadamard matrix is a unitary matrix where all elements are 1 or -1. For N>2 it is necessary that rem(N,4)=0 for a Hadamard matrix to exist. It is conjectured that this is also sufficient. bbhadamard requires that N can be factorized as a product of 2, 12, 20, 28, 36, and 44. An operator near the requested size can be retrieved as follows: [BB,N2]=bbhadamard(N,'next') Ensure N2>=N [BB,N2]=bbhadamard(N,'prev') Ensure N2<=N N2 is the order of the generated operator. See also .