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Dual-tree and double-density 1-D wavelet transform

returns the `wt`

= dddtree(`typetree`

,`x`

,`level`

,`fdf`

,`df`

)`typetree`

discrete wavelet transform (DWT) of the 1-D input
signal, `x`

, down to level, `level`

. The wavelet transform
uses the decomposition (analysis) filters, `fdf`

, for the first level and the
analysis filters, `df`

, for subsequent levels. Supported wavelet transforms
are the critically sampled DWT, double-density, dual-tree complex, and dual-tree double-density
complex wavelet transform. The critically sampled DWT is a filter bank decomposition in an
orthogonal or biorthogonal basis (nonredundant). The other wavelet transforms are oversampled
filter banks.

uses
the filters specified in `wt`

= dddtree(`typetree`

,`x`

,`level`

,`fname1`

,`fname2`

)`fname1`

for the first
stage of the dual-tree wavelet transform and the filters specified
in `fname2`

for subsequent stages of the dual-tree
wavelet transform. Specifying different filters for stage 1 is valid
and necessary only when `typetree`

is `'cplxdt'`

or `'cplxdddt'`

.