About alternatives to Matlab

sturlamolden sturlamolden at yahoo.no
Sat Nov 18 20:45:27 CET 2006


sturlamolden wrote:

> God grief. I followed the implementation in Ingrid Daubechies' and Wim
> Sweldens' original wavelet lifting paper  (J. Fourier Anal. Appl., 4:
> 247-269, 1998). If you look at the factorized polyphase matrix for D4
> (which gives the inverse transform), their implementation of the
> lifting steps the original paper is incorrect. That is scary.
>
> A free PDF or PS of the paper is available here:
>
> http://cm.bell-labs.com/who/wim/papers/factor/index.html


Actually its more complicated than that. The PS and the PDF files are
different, and only the PS-file is confused. Here is the correct
explanation:

The factorization of the polyphase matrix is not unique. There are
several valid factorizations. Our implementations corresponds to
different factorizations of the analysis and synthesis poyphase
matrices, and both are in a sence correct, although numerically
different.




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