# iir_bessel

Version:
Last Modified: March 15, 2017

Designs an analog Bessel filter. If you specify w, this function generates a lowpass filter of order n. If you specify w1 and w2, this function generates a bandpass filter of order 2n. [z, p, k] and [as, bs, cs, ds] generate the zero-pole-gain representation and the state-space representation, respectively, of the filter.

## Syntax

[b, a] = iir_bessel(n, w)
[b, a] = iir_bessel(n, [w1,w2])
[b, a] = iir_bessel(n, w, option)
[b, a] = iir_bessel(n, [w1,w2], 'stop')
[z, p, k] = iir_bessel(n, w)
[z, p, k] = iir_bessel(n, [w1,w2])
[z, p, k] = iir_bessel(n, w, option)
[z, p, k] = iir_bessel(n, [w1,w2], 'stop')
[as, bs, cs, ds] = iir_bessel(n, w)
[as, bs, cs, ds] = iir_bessel(n, [w1,w2])
[as, bs, cs, ds] = iir_bessel(n, w, option)
[as, bs, cs, ds] = iir_bessel(n, [w1,w2], 'stop')
Legacy name: besself

## n

Filter order. n is a positive integer.

## w

Cutoff frequency of the filter. w is a real number.

## [w1,w2]

Low and high cutoff frequency as matrix. w1 must fall in the range [0, 1]. If you specify 's', w1 can be any positive number. w2 must fall in the range [0, 1] and must be greater than w1. If you specify 's', w2 can be any positive number.

## option

Type of filter to design. option is a string that accepts the following values:

Name Description
'low'

Designs a lowpass filter.

'high'

Designs a highpass filter.

Default: 'low'

## 'stop'

Directs MathScript to design a stopband filter. If you do not specify 'stop' and you specify w1 and w2, MathScript designs a bandpass filter.

## b

Numerator of the filter under design. b is the forward filter coefficient of order n. b is a real vector.

## a

Denominator of the filter under design. a is the backward filter coefficient of order n. a is a real vector.

## z

Zeros of the filter. z is a vector.

## p

Poles of the filter. p is a vector.

## k

Gain of the filter. k is a real number.

## as

A coefficients of the filter. as is a matrix.

## bs

B coefficients of the filter. bs is a matrix.

## cs

C coefficients of the filter. cs is a matrix.

## ds

D coefficients of the filter. ds is a matrix.

N = 5;
W = 0.4;
[B, A] = iir_bessel(N, W)

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices