- Ajuda do Scilab
- Processamento de Sinais
- filters
- analpf
- buttmag
- casc
- cheb1mag
- cheb2mag
- convol
- ell1mag
- eqfir
- eqiir
- faurre
- ffilt
- filter
- find_freq
- frmag
- fsfirlin
- group
- iir
- iirgroup
- iirlp
- kalm
- lev
- levin
- lindquist
- remez
- remezb
- srfaur
- srkf
- sskf
- syredi
- system
- trans
- wfir
- wiener
- wigner
- window
- yulewalk
- zpbutt
- zpch1
- zpch2
- zpell

Please note that the recommended version of Scilab is 6.1.1. This page might be outdated.

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# filter

filters a data sequence using a digital filter

### Calling Sequence

[y,zf] = filter(B, A, x [,zi])

### Arguments

- B
real vector : the coefficients of the filter numerator in decreasing power order, or a polynomial.

- A
real vector : the coefficients of the filter denominator in decreasing power order, or a polynomial.

- x
real row vector : the input signal

- zi
real row vector of length

`max(length(a),length(b))-1`

: the initial condition relative to a "direct form II transposed" state space representation. The default value is a vector filled with zeros.- y
real row vector : the filtered signal.

- zf
real row vector : the final state. It can be used to filter a next batch of the input signal.

### Description

This function filters a data sequence using a digital filter using a "direct form II transposed" implementation.

The filter canonical form is :

The algorithm uses the highest degree between `degree(a)`

and `degree(b)`

as value for `n`

.

If the polynomial form is used for `B`

(resp. for `A`

) then a polynomial or a scalar must be used for `A`

(resp. `B`

).

### References

Oppenheim, A. V. and R.W. Schafer. Discrete-Time Signal Processing, Englewood Cliffs, NJ: Prentice-Hall, 1989, pp. 311-312.

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