find the longest diagonal sum of a matrix.

function largestDiagonalSum = diag_sum(matrix)
[rows,cols] = size(matrix);
largestDiagonalSum = 0;
for row = 1:rows
    for col = 1:cols
        diagonalSum = 0;
        for dr = [-1, -1, 1, 1]
            for dc = [-1, 1, -1, 1]
                r = row + dr;
                c = col + dc;
                if r >= 1 && r <= rows && c >= 1 && c <= cols
                    diagonalSum = diagonalSum + matrix(r, c);
                end
            end
        end
        if diagonalSum > largestDiagonalSum
            largestDiagonalSum = diagonalSum;
        end
    end
end
% Divide the largest diagonal sum by 4
largestDiagonalSum = largestDiagonalSum / 4;
end 

im not too woried aboout my code as it has to be just good eniugh to get me throiugh this semester of uni, though i keep getting ther erro

>> diag_sum

Not enough input arguments.

Error in diag_sum (line 2)

[rows, cols] = size(matrix);

Answer 1

[Walter Roberson]

When you press the green Run button, that is equivalent to running the function from the command line with no parameters.

When you run a function and do not pass parameters to it, then inside the function, any variable named on the function line remains undefined (unless you assign it a value.)

Under no circumstances will MATLAB go hunting around in the calling environment trying to find a variable named in the function line to use the value of inside the function.

Answer 2

[Image Analyst]

Assign something to matrix first, like

m = magic(5)

then call your function

largestDiagonalSum = diag_sum(m)