Here you'd need to define the purpose of using GF.
If you are aiming to select any randomly selected values of GF while computing the wave form fcn values, this can be done with the followings:
Fs = 1000; % Sampling frequency
T = 1/Fs; % Sampling period
L = 1024; % Length of signal
t = 2*(0:L-1)*T; % Time vector
signal = 0;
m = 5;
x = [0 1 1; 0 1 0; 1 1 1];
for k=1:((2^m)-1)
g =gf(x,m);
G = g.x(:);
signal = signal + double(G(randi(numel(G))))*exp(1i*2*pi*k*t)/((2^m)-1);
end
figure
subplot(2,2,1)
plot(t,real(signal))
title('signal: RE')
subplot(2,2,2)
plot(t,imag(signal))
title('signal: IM')
