i dont know why my code is not working..

if true
fs = 200; 
Ts = 1/fs; 
t = 0:Ts:50; % Zaman vektörü
u2=sin(2.*pi.*(1+5.*t).*t);
N=ceil(log2(length(u2)));
for k=1:N
  X(k)=0;
  for n=1:N
      X(k)=X(k)+u2(n).*exp(-1j.*2.*pi.*(n-1).*(k-1)./N);
  end
end 
Pyy=X.*conj(X);
f=fs*(0:(2^(N-1)-1))/2^N;
figure(1),plot(f,Pyy(1:2^(N-1)));
[MAX, MAXidx] = max(Pyy(1:2^(N-1)));
hold on
plot(f(MAXidx), MAX,'or')
end

Index exceeds matrix dimensions.

Answer 1

[Yona]

plot(f,Pyy(1:2^(N-1)));

the length of pyy in 14 so you cannot take cell number 16384 (2^13).

another problem: length(f)=8196 so length(Pyy) need to be the same.

[okan]

sorry im new on matlab so how can i fix that ?

[okan]

btw when i use that

if true
  fs = 200; % Örnekleme frekansı fs
Ts = 1/fs; % Öernekleme periyodu Ts
% Oluşturacağımız sinyaldeki frekanslar
t = 0:Ts:50; % Zaman vektörü
u2=sin(2.*pi.*(1+5.*t).*t);
noise=u2+0.5*randn(size(t));
N=ceil(log2(length(u2)));
X=fft(noise);
Pyy=X.*conj(X);
f=fs*(0:(2^(N-1)-1))/2^N;
figure(1),plot(f,Pyy(1:2^(N-1)));
[MAX, MAXidx] = max(Pyy(1:2^(N-1)));
hold on
plot(f(MAXidx), MAX,'or')
figure(1),ylabel('Genlik');
figure(1),xlabel('Zaman (s)');
figure(1),grid;
end
its working but i shouldn't use fft command for my homework

[Yona]

In your error-file length(X)=14 and in correct-file it 1001. try to check why it append, it probably will fix your problem