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A240908
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The sequency numbers of the 8 rows of a version of the Hadamard-Walsh matrix of order 8.
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4
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OFFSET
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1,2
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COMMENTS
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The Hadamard (Hadamard-Walsh) matrix is widely used in telecommunications and signal analysis. It has 3 well-known forms which vary according to the sequency ordering of its rows: "natural" ordering, "dyadic" or Payley ordering, and sequency ordering. In a mathematical context the sequency is the number of zero crossings or transitions in a matrix row (although in a physical signal context, it is half the number of zero crossings per time period). The matrix row sequencies are a permutation of the set [0,1,2,...n-1], where n is the order of the matrix. For spectral analysis of signals the sequency-ordered form is needed. Unlike the dyadic ordering (given by A153141), the natural ordering requires a separate list for each matrix order. This sequence is the natural sequency ordering for an order 8 matrix.
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LINKS
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FORMULA
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Recursion: H(2)=[1 1; 1 -1]; H(n) = H(n-1)*H(2), where * is Kronecker matrix product.
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EXAMPLE
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This is a fixed length sequence of only 8 values, as given.
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CROSSREFS
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Cf. A240909 "natural order" sequencies for Hadamard-Walsh matrix, order 16.
Cf. A240910 "natural order" sequencies for Hadamard-Walsh matrix, order 32.
Cf. A153141 "dyadic order" sequencies for Hadamard-Walsh matrix, all orders.
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KEYWORD
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nonn,fini,full
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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