Frequency response of analog filters
Compute the s-plane frequency response of an IIR filter.
freqs(filt, ...) ## Default S3 method: freqs(filt, a, w, plot = TRUE, ...) ## S3 method for class 'Arma' freqs(filt, w, ...) ## S3 method for class 'Ma' freqs(filt, w, ...) ## S3 method for class 'Sos' freqs(filt, w, ...) ## S3 method for class 'Zpg' freqs(filt, w, ...)
filt |
for the default case, moving average (MA) polynomial
coefficients, specified as a numeric vector or matrix. In case of a matrix,
then each row corresponds to an output of the system. The number of columns
of |
... |
additional parameters (not used) |
a |
autoregressive (AR) polynomial coefficients, specified as a vector. |
w |
angular frequencies, specified as a positive real vector expressed in rad/second. |
plot |
logical. If |
The s-plane frequency response of the IIR filter B(s) / A(s) is
computed as H = polyval(B, 1i * W) / polyval(A, 1i * W). If called
with no output argument, a plot of magnitude and phase are displayed.
Frequency response, returned as a complex vector.
Julius O. Smith III, jos@ccrma.stanford.edu.
Conversion to R by Geert van Boxtel gjmvanboxtel@gmail.com
b <- c(1, 2); a <- c(1, 1) w <- seq(0, 4, length.out = 128) freqs (b, a, w)
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