What are the ways to sum matrix elements in MATLAB?

Question

Given the matrix:

A = [1 2 3; 4 5 6; 7 8 9];

1. How could you use a for loop to compute the sum of the elements in the matrix?
2. Writ

Answer 1

Another answer for the first question is to use one for loop and perform linear indexing into the array using the function NUMEL to get the total number of elements:

total = 0;
for i = 1:numel(A)
  total = total+A(i);
end