Compute the sum of perimeter of matrix

My TA ask me to make a function code for this specific homework : computes the sum of the elements of an input matrix A that are on the “perimeter” of A.

This is what I have tried so far

function : sum=(A)
M= 2*(sum(A(1,1:end)) + sum(A(1:end,1)) + sum(A(end,1:end)) + sum(A(1:end,end))
end

please help me explain whether i am wrong or right

[James Tursa]

What is the 2 for? Did you try some examples to see if your code produces what you expect? Does your code count the corner elements twice?

Answer 1

[Jemima Pulipati]

Similar question has already been answered by the community which could be relevant to you. Please refer to the following link.

https://www.mathworks.com/matlabcentral/answers/298528-how-can-i-find-the-sum-of-the-perimeter-of-a-matrix

There is also a function in MathWorks File Exchange which could help you but the matrix should have each dimension atleast 2

https://www.mathworks.com/matlabcentral/fileexchange/71595-sum-of-values-on-the-perimeter-of-a-matrix