% test of myfft implementation

N = 128;
x = randn(N,1) + i*randn(N,1);
y0= fft(x);
y1= myfft(x);
norm(y0-sqrt(N)*y1)/norm(y0)

% computational complexity
Ns  = 2.^(1:16);
Nops= zeros(size(Ns));
for N=Ns,
    x = randn(N,1) + i*randn(N,1);
    [y,nop] = myfft(x);
    Nops(round(log2(N))) = nop;
end
loglog(Ns,Nops,'rx',...
       Ns,log2(Ns).*(2*Ns-1),'b',...
       Ns,2*Ns-1,'m');
grid on;
xlabel('N');
ylabel('complexity');
legend('FFT','O(N log(N))','O(N)',...
       'Location','Best');