% -*- texinfo -*-
% @deftypefn {Function File} {[@var{h}, @var{w}] =} freqz (@var{b}, @var{a}, @var{n}, 'whole')
% Return the complex frequency response @var{h} of the rational IIR filter
% whose numerator and denominator coefficients are @var{b} and @var{a},
% respectively. The response is evaluated at @var{n} angular frequencies
% between 0 and
% @ifnottex
% 2*pi.
% @end ifnottex
% @tex
% $2\pi$.
% @end tex
%
% @noindent
% The output value @var{w} is a vector of the frequencies.
%
% If the fourth argument is omitted, the response is evaluated at
% frequencies between 0 and
% @ifnottex
% pi.
% @end ifnottex
% @tex
% $\pi$.
% @end tex
%
% If @var{n} is omitted, a value of 512 is assumed.
%
% If @var{a} is omitted, the denominator is assumed to be 1 (this
% corresponds to a simple FIR filter).
%
% For fastest computation, @var{n} should factor into a small number of
% small primes.
%
% @deftypefnx {Function File} {@var{h} =} freqz (@var{b}, @var{a}, @var{w})
% Evaluate the response at the specific frequencies in the vector @var{w}.
% The values for @var{w} are measured in radians.
%
% @deftypefnx {Function File} {[@dots{}] =} freqz (@dots{}, @var{Fs})
% Return frequencies in Hz instead of radians assuming a sampling rate
% @var{Fs}. If you are evaluating the response at specific frequencies
% @var{w}, those frequencies should be requested in Hz rather than radians.
%
% @deftypefnx {Function File} {} freqz (@dots{})
% Plot the pass band, stop band and phase response of @var{h} rather
% than returning them.
% @end deftypefn