How do you initialize an N*M matrix?

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Harry
Harry on 26 Jun 2013
Answered: HARSHAVARTHINI on 26 Nov 2024 at 6:21
From the MATLAB help, it says to use:
M = matrix(N, M)
but when I apply this it says that the function 'matrix' is not recognized.
Undefined function 'matrix' for input arguments of type 'double'.
Error in experimental (line 1)
M = matrix(3,3)

Accepted Answer

Leah
Leah on 26 Jun 2013
Edited: MathWorks Support Team on 27 Nov 2018
To initialize an N-by-M matrix, use the “zeros” function. For example, create a 3-by-5 matrix of zeros:
A = zeros(3,5);
You can then later assign specific values to the elements of “A”.
  3 Comments
Abhishek Inamdar
Abhishek Inamdar on 6 Jul 2021
Use "X = ones(n)" and add the values based on the row and column. Use for loop to work on value addition
israt fatema
israt fatema on 25 Aug 2021
Can you please show me how to assign value to A after initialize the N x M matrix? For example i need to create a vector 5 x 5 and with values x = 20 35 49 64 23

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More Answers (5)

Lokesh Ravindranathan
Lokesh Ravindranathan on 26 Jun 2013
Edited: Lokesh Ravindranathan on 26 Jun 2013
I am assuming you are trying to create an empty matrix of zeros of dimensions N*M. You can try the following instead
M = zeros(3,3)
This creates a matrix of zeros of size 3*3.
  2 Comments
per isakson
per isakson on 26 Jun 2013
Edited: per isakson on 26 Jun 2013
matrix is a function in the symbolic toolbox.
Lokesh Ravindranathan
Lokesh Ravindranathan on 26 Jun 2013
Oh. Thanks Isakson. I will update my answer. My MATLAB did not have symbolic Math toolbox.

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Nitin
Nitin on 26 Jun 2013
you could initialize the matrix,
M = zeros(n,m);

Pau
Pau on 17 Oct 2018
This should make the trick
M = double.empty(N,M,0);
https://uk.mathworks.com/help/matlab/ref/empty.html

Arun
Arun on 7 Dec 2022
Edited: Arun on 7 Dec 2022
Here is the documentation for multi dementional arrays in matlab
Here is an example to create and initialize a 3X3 matric
A = [1 2 3; 4 5 6; 7 8 9]
A = 3×3
1 2 3
4 5 6
7 8 9
It is simular to matrix in c programming.

HARSHAVARTHINI
HARSHAVARTHINI on 26 Nov 2024 at 6:21

% Define the matrix A = [4 1 9; 0 1 3; 0 1 2];

% Initialize parameters n = size(A, 1); % Size of the matrix x = rand(n, 1); % Initial guess for the eigenvector tolerance = 1e-6; % Convergence criteria max_iter = 1000; % Maximum number of iterations lambda_old = 0; % Initial eigenvalue

for k = 1:max_iter % Multiply matrix A with vector x y = A * x;

    % Normalize the vector
    x = y / norm(y);
    % Compute the Rayleigh quotient (dominant eigenvalue)
    lambda = x' * A * x;
    % Check for convergence
    if abs(lambda - lambda_old) < tolerance
        fprintf('Converged in %d iterations.\n', k);
        break;
    end
    % Update old eigenvalue
    lambda_old = lambda;
end

% Display results fprintf('Dominant Eigenvalue: %.6f\n', lambda); disp('Corresponding Eigenvector:'); disp(x);

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