以下内容来自matlab help，发出来是为了自己查阅方便。

wfilters

Wavelet filters

Syntax

• [Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('wname')
  [F1,F2] = wfilters('wname','type')
  

Description

[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('wname') computes four filters associated with the orthogonal or biorthogonal wavelet named in the string 'wname'.

The four output filters are

• Lo_D, the decomposition low-pass filter
• Hi_D, the decomposition high-pass filter
• Lo_R, the reconstruction low-pass filter
• Hi_R, the reconstruction high-pass filter

Available orthogonal or biorthogonal wavelet names 'wname' are listed in the table below.

[F1,F2] = wfilters('wname','type') returns the following filters:

Examples

• % Set wavelet name. 
  wname = 'db5';
  
  % Compute the four filters associated with wavelet name given 
  % by the input string wname. 
  [Lo_D,Hi_D,Lo_R,Hi_R] = wfilters(wname); 
  subplot(221); stem(Lo_D); 
  title('Decomposition low-pass filter'); 
  subplot(222); stem(Hi_D); 
  title('Decomposition high-pass filter'); 
  subplot(223); stem(Lo_R); 
  title('Reconstruction low-pass filter'); 
  subplot(224); stem(Hi_R); 
  title('Reconstruction high-pass filter'); 
  xlabel('The four filters for db5')
  
  % Editing some graphical properties,
  % the following figure is generated.
  
  
  
  http://s5/middle/4abb4facgbe15db55d954&690
  
  

References

Daubechies, I. (1992), Ten lectures on wavelets, CBMS-NSF conference series in applied mathematics. SIAM Ed.

Mallat, S. (1989), "A theory for multiresolution signal decomposition: the wavelet representation," IEEE Pattern Anal. and Machine Intell., vol. 11, no. 7, pp. 674-693.