<< upwlev2 discrete_wavelet_analysis wavedec2 >>

swt >> discrete_wavelet_analysis > wavedec

wavedec

Multiple level 1-D discrete fast wavelet decomposition

Calling Sequence

[C,L]=wavedec(X,N,wname)
[C,L]=wavedec(X,N,Lo_D,Hi_D)

Parameters

wname :

wavelet name, haar( "haar"), daubechies ("db1" to "db36"), coiflets ("coif1" to "coif17"), symlets ("sym2" to "sym20"), legendre ("leg1" to "leg9"), bathlets("bath4.0" to "bath4.15" and "bath6.0" to "bath6.15"), dmey ("dmey"), beyklin ("beylkin"), vaidyanathan ("vaidyanathan"), biorthogonal B-spline wavelets ("bior1.1" to "bior6.8"), "rbior1.1" to "rbior6.8"

X :

signal vector

N :

decompostion level

Lo_D :

lowpass analysis filter

Hi_D :

highpass analysis filter

C :

coefficient vector

L :

length vector

Description

wavedec can be used for multiple-level 1-D discrete fast wavelet decompostion using a specific wavelet name wname or wavelet decompostion filters Lo_D and Hi_D. Such filters can be generated using wfilters.

The global extension mode which can be change using dwtmode is used.

The coefficient vector C contains the approximation coefficient at level N and all detail coefficient from level 1 to N

The first entry of L is the length of the approximation coefficent, then the length of the detail coefficients are stored and the last value of L is the length of the signal vector.

The approximation coefficient can be extracted with C(1:L(1)). The detail coefficients can be obtained with C(L(1):sum(L(1:2))), C(sum(L(1:2)):sum(L(1:3))),.... until C(sum(L(1:length(L)-2)):sum(L(1:length(L)-1))).

Examples

X = wnoise(4,10,0.5); //doppler with N=1024
[C,L]=wavedec(X,3,'db2');
scf();clf();
subplot(511)
plot(X,'r')
subplot(512)
plot(C(1:L(1)))
subplot(513)
plot(C(L(1):sum(L(1:2))),'g')
subplot(514)
plot(C(sum(L(1:2)):sum(L(1:3))),'g')
subplot(515)
plot(C(sum(L(1:3)):sum(L(1:4))),'g')

See also

Authors


Report an issue
<< upwlev2 discrete_wavelet_analysis wavedec2 >>