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fejerkorovkin

Fejer-Korovkin wavelet filters

Syntax

Lo = fejerkorovkin(wname)

Description

example

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

Examples

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

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

Lo = fejerkorovkin('fk14')
Lo = 

  Columns 1 through 7

    0.2604    0.6869    0.6116    0.0514   -0.2456   -0.0486    0.1243

  Columns 8 through 14

    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 = 

  Columns 1 through 7

    0.0035    0.0093   -0.0033   -0.0298   -0.0051    0.0640    0.0222

  Columns 8 through 14

   -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

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Filter name, specified as a character vector. The numeric value in each name is the number of Fejer-Korovkin filter coefficients.

Output Arguments

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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, pp. 36–52.

See Also

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Introduced in R2015b

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