function [tfd, t, f] = page2(x, fs, nfreq)% page2 -- Compute samples of the type II Page distribution.%%  Usage%    [tfd, t, f] = page2(x, fs, nfreq)%%  Inputs%    x     signal vector%    fs    sampling frequency of x (optional, default is 1 sample/second)%    nfreq number of samples to compute in frequency (optional, default%          is twice the length of x)%%  Outputs%    tfd  matrix containing the binomial distribution of signal x.  If x has%         length N, then tfd will be nfreq by N. (optional)%    t    vector of sampling times (optional)%    f    vector of frequency values (optional)%% If no output arguments are specified, then the Page distribution is % displayed using ptfd(tfd, t, f).% Copyright (C) -- see DiscreteTFDs/Copyright% specify defaultsx = x(:);N = length(x);error(nargchk(1, 3, nargin));if (nargin < 3)  nfreq = 2*N;endif (nargin < 2)  fs = 1;end% positive tauacf = zeros(N);for t=1:N;  gacf(1:N-t+1,t) = x(t) * conj(x(t:N));end% negative taugacf = [gacf ; zeros(nfreq-2*N+1,N) ; conj(flipud(gacf(2:N,:)))];%compute the tfdtfd = real(fft(gacf));tfd = tfdshift(tfd)/nfreq;t = 1/fs * (0:N-1);f = -fs/2:fs/nfreq:fs/2;f = f(1:nfreq);if (nargout == 0)  ptfd(tfd, t, f);  clear tfdend