How can I implement this code several stages??

I want to compute 15 stages of the my output , my problem is in the second loop, is it correct?? i want to implement yi+1(n) = yi(n) * wi+1 ie: y1(n) is the first stage and so on...when i run it i get Index exceeds matrix dimensions. error in y(i+1,:)=y(i)*w(i+1,:);

also, how can i plot the fourth stage??? thank you for the help.

%    w = estimated FIR filter
%     y = output array y(n)
%     x = input array x(n)
%     d = desired array d(n), length must be same as x
%     mu = step size
% M=order of the filter;
        N=300;    
        n=1:N; 
        M=4;
        d(n) = sin(0.2*pi*n);
        sigma = 0.5;  
        v(n) =sigma*randn(1,N);
        x(n)= d+v; N=length(x);        
        subplot(311); plot(d(n))
        mu=0.01; subplot(312); plot(x(n))
        w=zeros(1,M);  w1=zeros(1,M);e=zeros(1,N);y=zeros(1,N);
for n=M:N
 x1=x(n:-1:n-M+1);
 y(n) = w*x1';
  e = d(n)-y(n);
  w = w +mu*e*x1;
 w1(n-M+1,:)=w(1,:);
end
% I is number of stages
I=15;
for i=2:I
  y(i+1,:)=y(i)*w(i+1,:);
end

[dpb]

M and d are undefined for starters...

[KALYAN ACHARJYA]

Please provide the complete information (all input data) to get the exact solution.

[Adam Danz]

Still not enough information.

We need a working example so we can run your code. There are missing variable values and the code in your comment above is not executable. To move forward, provide a functional code that you've tested and we can copy-paste into our environment.

[Adam Danz]

We still can't run the code.

Unrecognized function or variable 'M1'.
Error in jff (line 18)
    x1=x(n:-1:n-M1+1); 

[Good mind]

Sorry, it is typo. it is M not M1

[Walter Roberson]

M=4;
w=zeros(1,M);

okay so w is 1 x 4

w = w +mu*e*x1;

mu and e are scalars and x1 is 1 x 4, so w stays 1 x 4

I=15;
for i=2:I
  y(i+1,:)=y(i)*w(i+1,:);
end

That asks for row number 2+1=3 of w, but w only has 1 row.

[Good mind]

Is the second loop correct???? in my case:the future out put is dependent on the present out put and the future filter

[Walter Roberson]

How can it be correct when you are asking for multiple rows of w when w only has one row?