"Error using *". Help with my Monte Carlo Simulation

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Karim Wahdan 2021-1-25

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https://ww2.mathworks.cn/matlabcentral/answers/726628-error-using-help-with-my-monte-carlo-simulation

编辑： Image Analyst 2022-6-8

I have created code on low rank assumption using nuclear norm using CVX. I'm thinking this error code is being caused by the variable X not being recognised but im not sure. Here is the following error code -

Error using *

Incorrect dimensions for matrix multiplication. Check that the

number of columns in the first matrix matches the number of rows

in the second matrix. To perform elementwise multiplication, use

'.*'.

Error in Untitled34 (line 36)

y(i_p) = trace(M_p{i_p}*X);

Related documentation

Here is my code :

clear all; 
clc; 
MONTE_CARLO = 10;
n = 10;
m = 20;
k = 5;
U = randn(m,k);
V = randn(k,n);
X = U*V
for p = 1 : 50  : n^2          % Number of measurements    
    for mc = 1 : MONTE_CARLO   % Monte Carlo simulations        
        M_p = cell(p, 1);      % Cell with measurement matrices        
        y = zeros(p, 1);       % Vector of measurements        
        for i_p = 1 : p        % Generate measurement matrices            
            M_p{i_p} = randn(n, n);            
            y(i_p) = trace(M_p{i_p}*X);            
        end
        cvx_begin        
        variable Xe(n,n);        
        minimize(norm_nuc(Xe));        
        subject to
        
        for i_p = 1 : p            
            trace(Xe*M_p{i_p}) == y(i_p);
        end
        cvx_end
    end
end

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Karim Wahdan 2021-1-27

@Bob Thompson What would you recommend then to fix this issue?

Bob Thompson 2021-1-27

I don't know, because I don't know your problem statement to understand what X is supposed to be, or why you need a square matrix. It seems to me that this is not a MATLAB specific issue, and I recommend taking another look at the purpose for your code, rather than the specifics of the code itself. Sorry I can't be more help.

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