For Loop /Array question

How would i go about creating a for loop to create an array where each value in X is equal to its associated row value * 2 plus its associated column value * 3 +1. Size of array is 50x50 ?

[James Tursa]

What have you done so far? What specific problems are you having with your code? Do you know how to write a for-loop? Do you know how to pre-allocate a 50x50 matrix?

[Tyler Young]

I know how to write simpler for loops where I can identify a "start" point for my indx and run through a simple array or vector to "end" but Im struggling to comprehend how to build the value of this equation.

Answer 1

[Hiro Yoshino]

How about this?:

X = zeros(50, 50);
[m, n] = size(X); % m x n = 50, 50

for i = 1:m % Row
    for j = 1:n % Column
        X(i, j) = i * 2 + j * 3 + 1;
    end
end

(m, n) could be anytihng.

The point here is size function. Good luck!

[Tyler Young]

Thank you, that does work, and helps to see it done that way too. I ended up going about it differently, but I was orginally thinking of using "zeros"

for row = 1:1:50
    for col = 1:1:50
       X(row,col) = [row * 2 + col * 3 + 1]
    end
end    

Answer 2

[KSSV]

Check the below deom code where each element of a matrix is sum of its row and column position. Extend this to your case.

m = 5 ;   % number of rows 
n = 5 ;  % number of columns 
iwant = zeros(m,n) ;    % initialize the required matrix 
% loop 
for i = 1:m   % loop for row
    for j = 1:n   % loop for column 
        iwant(i,j) = i+j ;   %(i,j)th  element is sum of i and j 
    end
end

[Tyler Young]

Thank you, appreciate the multiple ways of seeing this done.