buttap {gsignal}

Butterworth filter prototype

Description

Return the poles and gain of an analog Butterworth lowpass filter prototype.

Usage

buttap(n)

Arguments

n

Order of the filter.

Details

This function exists for compatibility with 'Matlab' and 'Octave' only, and is equivalent to butter(n, 1, "low", "s").

Value

List of class Zpg containing poles and gain of the filter.

Author(s)

Carne Draug, [e-mail].
Conversion to R by Geert van Boxtel, [e-mail].

Examples

## 9th order Butterworth low-pass analog filter
zp <- buttap(9)
w <- seq(0, 4, length.out = 128)
freqs(zp, w)