Summing elements of any vector using a for loop?

How would I write code to sum all of the elements of any vector (ie a generic functions which can be applied to any vector) using a for loop? Here is what I have tried and I am stuck because there is an error in line 5 (for X).

My code:

function S = mySum(X)
%MYSUM  Sum of elements
%   S = MYSUM(X) is the sum of the elements of the vector
adder = 0
for X 
    adder = adder + X

end
 S = adder + X

Answer 1

[Image Analyst]

No need for both adder and S. Simply have this:

function S = mySum(X)
% MYSUM  Sum of elements
% S = mySum(X) is the sum of the elements of the vector or array X.
% Works for X of any number of dimensions and sizes.
S = 0;
for k = 1 : numel(X)
  S = S + X(k);  
end