SymletWavelet

SymletWavelet[]

represents the Symlet wavelet of order 4.

SymletWavelet[n]

represents the Symlet wavelet of order n.

Details

  • SymletWavelet, also known as "least asymmetric" wavelet, defines a family of orthogonal wavelets.
  • SymletWavelet[n] is defined for any positive integer n.
  • The scaling function () and wavelet function () have compact support length of 2n. The scaling function has n vanishing moments.
  • SymletWavelet can be used with such functions as DiscreteWaveletTransform and WaveletPhi, etc.

Examples

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Basic Examples  (3)

Scaling function:

Wavelet function:

Filter coefficients:

Scope  (14)

Basic Uses  (8)

Compute primal lowpass filter coefficients:

Primal highpass filter coefficients:

Lifting filter coefficients:

Generate a function to compute lifting wavelet transform:

Symlet scaling function of order 4:

SymletWavelet of order 10:

Plot scaling function using different levels of recursion:

Symlet wavelet function of order 4:

SymletWavelet of order 10:

Plot scaling function using different levels of recursion:

Wavelet Transforms  (5)

Compute a DiscreteWaveletTransform:

View the tree of wavelet coefficients:

Get the dimensions of wavelet coefficients:

Plot the wavelet coefficients:

Compute a DiscreteWaveletPacketTransform:

View the tree of wavelet coefficients:

Get the dimensions of wavelet coefficients:

Plot the wavelet coefficients:

Compute a StationaryWaveletTransform:

View the tree of wavelet coefficients:

Get the dimensions of wavelet coefficients:

Plot the wavelet coefficients:

Compute a StationaryWaveletPacketTransform:

View the tree of wavelet coefficients:

Get the dimensions of wavelet coefficients:

Plot the wavelet coefficients:

Compute a LiftingWaveletTransform:

View the tree of wavelet coefficients:

Get the dimensions of wavelet coefficients:

Plot the wavelet coefficients:

Higher Dimensions  (1)

Multivariate scaling and wavelet functions are products of univariate ones:

Applications  (3)

Approximate a function using Haar wavelet coefficients:

Perform a LiftingWaveletTransform:

Approximate original data by keeping n largest coefficients and thresholding everything else:

Compare the different approximations:

Compute the multiresolution representation of a signal containing an impulse:

Compare the cumulative energy in a signal and its wavelet coefficients:

Compute the ordered cumulative energy in the signal:

The energy in the signal is captured by relatively few wavelet coefficients:

Properties & Relations  (12)

Order 1 SymletWavelet is equivalent to HaarWavelet:

Lowpass filter coefficients sum to unity; :

Highpass filter coefficients sum to zero; :

Scaling function integrates to unity; :

In particular, :

Wavelet function integrates to zero; :

Wavelet function is orthogonal to the scaling function at the same scale; :

The lowpass and highpass filter coefficients are orthogonal; :

Order n of SymletWavelet indicates n vanishing moments; :

This means linear signals are fully represented in the scaling functions part ({0}):

Quadratic or higher-order signals are not:

satisfies the recursion equation :

Plot the components and the sum of the recursion:

satisfies the recursion equation :

Plot the components and the sum of the recursion:

Frequency response for is given by :

The filter is a lowpass filter:

The higher the order n, the flatter the response function at the ends:

Fourier transform of is given by :

Frequency response for is given by :

The filter is a highpass filter:

The higher the order n, the flatter the response function at the ends:

Fourier transform of is given by :

Possible Issues  (1)

SymletWavelet is restricted to n less than 20:

SymletWavelet is not defined when n is not a positive machine integer:

Neat Examples  (2)

Plot translates and dilations of scaling function:

Plot translates and dilations of wavelet function:

Introduced in 2010
 (8.0)