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Explanation of Notation
How does it work?

Haar Transform

The Haar transform, HT, is defined recursively by:

The following structured, sparse matrix factorization represents a fast algorithm for a HT, size 8, and has been automatically generated (even in the presented Latex format) using the package AREP.
fast algorithm HT
Note that this algorithm requires 8 multiplications and 14 additions and is thus among the best ones known.

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