A octave/MATLAB script to show how Nyquist's formula
Nyquist showed that if the function was band limited to less than Hz, then it could be represented by . This octave script checks this for finite values of in the sum, .
% This is a script to check Nyquist's formula giving a low pass % function as a function of its sample points, x(kT). % Note that the approximation is pretty good for -M*T<t<M*T. M=100; % Number of terms T=1e-4; Tf=.02; function x0 = x(t0) x0=sin(2*pi*180*t0)+cos(2*pi*50*t0); endfunction t=-Tf:T/1000:Tf; x1=zeros(size(t)); for k=-M:M x1 = x1 + x(k*T).*sinc((t-k*T)/T); end plot(t,x1,t,x(t)) title(strcat('Approximation: M*T =',num2str(M*T))) legend('seres','actual')