Wavelet Toolbox™

Biorthogonal scaling and wavelet functions

Syntax

• [PHIS,PSIS,PHIA,PSIA,XVAL] = bswfun(LoD,HiD,LoR,HiR)
  [PHIS,PSIS,PHIA,PSIA,XVAL] = bswfun(LoD,HiD,LoR,HiR,ITER)
  [PHIS,PSIS,PHIA,PSIA,XVAL] = bswfun(LoD,HiD,LoR,HiR,'plot')
  [PHIS,PSIS,PHIA,PSIA,XVAL] = bswfun(LoD,HiD,LoR,HiR,ITER,'plot')
  

Description

[PHIS,PSIS,PHIA,PSIA,XVAL] = bswfun(LoD,HiD,LoR,HiR) returns approximations on the grid XVAL of the two pairs of scaling function and wavelet (PHIA,PSIA), (PHIS,PSIS) associated with the two pairs of filters (LoD,HiD), (LoR,HiR).

bswfun(LoD,HiD,LoR,HiR,ITER) computes the two pairs of scaling and wavelet functions using ITER iterations.

bswfun(LoD,HiD,LoR,HiR,'plot') or bswfun(LoD,HiD,LoR,HiR,ITER,'plot') or bswfun(LoD,HiD,LoR,HiR,'plot',ITER) computes and plots the functions.

Examples

• % Start from the Cohen-Daubechies-Feauveau wavelet 
  % and get the corresponding lifting scheme.
  lscdf = liftwave('cdf3.1');
  
  % Visualize the obtained lifting scheme.
  displs(lscdf);
  
  lscdf = {...                                         
  'p'             [ -0.33333333]              [-1]  
  'd'             [ -0.37500000 -1.12500000]  [1]   
  'p'             [  0.44444444]              [0]   
  [  2.12132034]  [  0.47140452]              []    
  };                                                
  
  % Transform the lifting scheme to biorthogonal
  % filters quadruplet.
  [LoD,HiD,LoR,HiR] = ls2filt(lscdf);
  
  % Visualize the two pairs of scaling and wavelet
  % functions.
  bswfun(LoD,HiD,LoR,HiR,'plot');
  
  

Algorithm

This function uses the cascade algorithm.

See Also
wavefun

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