fs=1000; %czestotliwosc probkowania
f0=110;  %czestotliwosc sygnalu



for ind=10:15

N=2^ind;     %liczba probek sygnalu
t=(0:N-1)/fs;
x=cos(2*pi*f0*t);

%metoda bezposrednia
kern=1i*2*pi/N;
X=zeros(N,1);
Wrow2=exp(kern*(0:N-1));

t=cputime;
X(1)=ones(1,N)*x';
X(2)=Wrow2*x';

for k=3:N
    
    X(k)=exp((k-1)*kern*(0:N-1))*x';
end

elapsed_timeDirect(ind)=cputime-t

%  figure
%  subplot(2,1,1)
%  plot(1:N,real(X),1:N,imag(X))

%metoda FFT radix2
t=cputime;
X=myFFT(x');
elapsed_timeFFT(ind)=cputime-t

end
%% plot time
N=2.^(1:15);
figure
plot(1:length(elapsed_timeDirect),log10(elapsed_timeDirect),'x',1:length(elapsed_timeDirect),log10(elapsed_timeFFT),'o',...
    1:length(elapsed_timeDirect),log10(elapsed_timeDirect./N/1.*log2(N)))