buttap

Create a normalized Butterworth analog lowpass prototype filter in zero-pole-gain form.

Syntax

[z,p,k] = buttap(n)

Inputs

n
The filter order.
Type: integer
Dimension: scalar

Outputs

z
The zeros of the filter.
Type: vector
p
The poles of the filter.
Type: vector
k
The gain factor.
Type: scalar

Examples

Create a fourth order Butterworth analog prototype filter.

[z,p,k] = buttap(4)
z = [Matrix] 0 x 1
p = [Matrix] 4 x 1
-0.38268 + 0.92388i
-0.92388 + 0.38268i
-0.92388 - 0.38268i
-0.38268 - 0.92388i
k = 1

Comments

The Butterworth prototype has -3dB attenuation at a 1 radian/sec cutoff frequency. Analog Butterworth filters have no zeros.