My stochastic processes program

Hello My teacher Matt

 I have a program and When I asked my teacher if my solution is

true or not,he said to me that my solution is not correct

Please,could you help me

My program

N=400; %Define Number of samples((times))

f1=1; % Frequency of the cosinewave

FS=200; % Sampling Frequency

Q=0;

t=1:400;

n=0:N-1;

X1=0;

for i=1:400

for j=1:301

    X=cos((2*pi*f1*(n/FS))+Q);

 X1=X1+X;

    Q= -2*pi/N;

end 

Q=Q*2;

end

subplot(2,1,1); % Prepare the figure

plot(t,X1/(400*301)) % Plot mean value vs. t

grid;

title('mean value function of cosinewave ');

xlabel('Time index');

ylabel('Mean value');

Rxx=xcorr(X1); % Estimate its autocorrelation

subplot(2,1,2);

plot(Rxx); % Plot the autocorrelation

grid;

title('Autocorrelation function of the cosinewave');

xlabel('Time index');

ylabel('Autocorrelation');

My teacher at university said to me that I have mistake here and

he wrote this note but I did not understand what he mean!!!

X=cos((2*pi*f1*(n/FS))+Q); % Generate x(t)

Here X must be as X(i,j). Then it has 400 rows and 301 columns. Row number equals to the number of realizations

[Oleg Komarov]

Can you please format the code properly: http://www.mathworks.com/matlabcentral/answers/7885-tutorial-how-to-format-your-question

Answer 1

[Oleg Komarov]

You basically calculate the same X all the time. Nothing changes inside the loops.

[reem]

The theta Q is changed because I multiply it every time by 2 number

[Oleg Komarov]

Yes, by the same numbers, which means that it doesn't change.

[reem]

Yes,you are true

so I must apply that,isn't it???

Q1=Q1+Q

[Oleg Komarov]

Maybe, I don't know what is the stochastic process you have to reproduce.

Also, you probably have to change one of the input of X according to the indices i and j but the only vector you have in the expression is n (1 by 400) so you can use n(i), but this leaves the j index unused.