# Documentation

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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.

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