signal (version 0.5)

freqs: s-plane frequency response

Description

Compute the s-plane frequency response of an ARMA model (IIR filter).

Usage

## S3 method for class 'default':
freqs(filt = 1, a = 1, W, \ldots)

## S3 method for class 'Arma':
freqs(filt, \ldots)

## S3 method for class 'Ma':
freqs(filt, \ldots)

## S3 method for class 'freqs':
print(x, \ldots)

## S3 method for class 'freqs':
plot(x, \ldots)

## S3 method for class 'default':
freqs_plot(w, h, \ldots) 

## S3 method for class 'freqs':
freqs_plot(w, \ldots)

Arguments

filt

for the default case, the moving-average coefficients of an ARMA model or filter. Generically, filt specifies an arbitrary model or filter operation.

a

the autoregressive (recursive) coefficients of an ARMA filter.

W

the frequencies at which to evaluate the model.

w

for the default case, the array of frequencies. Generically, w specifies an object from which to plot a frequency response.

h

a complex array of frequency responses at the given frequencies.

x

object to be plotted.

...

additional arguments passed through to plot.

Value

• For freqs list of class freqs with items:
• H
  array of frequencies.
• W
  complex array of frequency responses at those frequencies.

Details

When results of freqs are printed, freqs_plot will be called to display frequency plots of magnitude and phase. As with lattice plots, automatic printing does not work inside loops and function calls, so explicit calls to print are needed there.

See Also

filter, Arma, freqz

Examples

b = c(1, 2)
a = c(1, 1)
w = linspace(0, 4, 128)
freqs(b, a, w)