While it is not documented, the ifft function is there. For example:
t=1:1024;
sample_rate=10e3;
fc=500;
x=sin(2*pi*t*fc/sample_rate);
xf=fft(x);
figure(1);
plot(abs(xf));
y=ifft(xf);
figure(2);
plot(real(y));
figure(3);
plot(x);
One thing to remember is that the output of the ifft function is a
complex vector. So, to plot it, you'll have to use the real function.
Please let me know if this works or if you have other problems.
Gary