fejerkorovkin

Fejér-Korovkin wavelet filters

Syntax

Lo = fejerkorovkin(wname)

Description

Lo = fejerkorovkin(wname) returns the Fejér-Korovkin scaling filter specified by wname. Valid entries for wname are 'fk4', 'fk6', 'fk8', 'fk14', 'fk18', and 'fk22'. For information on the Fejér–Korovkin filters, see Nielson[1].

Examples

Fejér-Korovkin Filters

Construct and plot the Fejér-Korovkin (14) scaling function and wavelet.

Obtain the Fejér-Korovkin scaling filter and display its 14 coefficients.

Lo = fejerkorovkin("fk14")

Lo = 1×14

    0.2604    0.6869    0.6116    0.0514   -0.2456   -0.0486    0.1243    0.0222   -0.0640   -0.0051    0.0298   -0.0033   -0.0093    0.0035

Use the scaling filter to obtain the wavelet filter and display its wavelet filter coefficients.

Hi = qmf(Lo)

Hi = 1×14

    0.0035    0.0093   -0.0033   -0.0298   -0.0051    0.0640    0.0222   -0.1243   -0.0486    0.2456    0.0514   -0.6116    0.6869   -0.2604

wavefun provides an efficient way to construct and plot the scaling function and wavelet.

[phi,psi,xval] = wavefun("fk14");
subplot(2,1,1)
plot(xval,phi)
title("Scaling Function")
subplot(2,1,2)
plot(xval,psi)
title("Wavelet")

Input Arguments

wname — Name

'fk4' | 'fk6' | 'fk8' | 'fk14' | 'fk18' | 'fk22'

Name of desired Fejér-Korovkin scaling filter. The numeric value in each name is the number of Fejér-Korovkin filter coefficients. For example, if wname is 'fk14', Lo has 14 coefficients.

Output Arguments

Lo — Scaling filter

vector

Scaling filter, returned as a vector.

References

[1] Nielsen, M. "On the construction and frequency localization of finite orthogonal quadrature filters." Journal of Approximation Theory. Vol. 108, Number 1, 2001, pp. 36–52.

Version History

Introduced in R2015b