Function Reference
— Function File: [h, w] = freqz (b, a, n, "whole")

Return the complex frequency response h of the rational IIR filter whose numerator and denominator coefficients are b and a, respectively. The response is evaluated at n angular frequencies between 0 and

The output value w is a vector of the frequencies.

If the fourth argument is omitted, the response is evaluated at frequencies between 0 and

If n is omitted, a value of 512 is assumed.

If a is omitted, the denominator is assumed to be 1 (this corresponds to a simple FIR filter).

For fastest computation, n should factor into a small number of small primes. — Function File: h = freqz (b, a, w)

Evaluate the response at the specific frequencies in the vector w. The values for w are measured in radians. — Function File: [...] = freqz (..., Fs)

Return frequencies in Hz instead of radians assuming a sampling rate Fs. If you are evaluating the response at specific frequencies w, those frequencies should be requested in Hz rather than radians. — Function File: freqz (...)

Plot the pass band, stop band and phase response of h rather than returning them.