What is wrong in this code? trying to code the equation and j is time instant

N= 10;
M = 4;
data = randi([0,3],999,1);
u = pammod(data,M);
x= zeros(24,24);%estimated 
for i = 1:N
    syms  i
    for j = 1:N
        
        H(:,k)= symsum ((x(i(:,j)))*(x(i+N(:,j))),i,1,N); 
    end
end

Answer 1

[Divyam]

Hi @Aastha Singla,

Here are a few corrections you can make in your code:

• The size of vector x should be , i.e. not .
• Matrix "H" and variable "k" need to be defined appropriately.
• No need to use "i" as a symbolic variable, it can function perfectly fine as a loop variable.
• Indexing used in the loop is incorrect and needs to be fixed.
• The sum can be directly computed numerically using a loop and "symsum" is not needed for the same.

x = [1; 2; 3; 4];

total_size = size(x, 1);
N = total_size/2;

% Initialize output matrix
H = zeros(N, N);

% Compute matrix H
for i = 1:N
    for j = 1:N
        % Calculate the sum for each element
        sum_val = 0;
        for k = 1:N
            % Ensure we don't exceed vector bounds
            if (k + j - 1) <= total_size
                sum_val = sum_val + x(k) * x(k + j - 1);
            end
        end
        H(i, j) = sum_val;
    end
end

disp(H);

     5     8
     5     8