how to sum a vector without sum function

function Mean = mean_strength(StrengthVector)
N = numel(StrengthVector);
x = sum(StrengthVector);
for i = 1:N 
  Mean = (1/N)*(x);
end

I need to change my code so I don't use the in built Matlab sum function.

Answer 1

[KL]

Your idea of using for loop is correct but you should use it to calculate the sum not the mean.

If there's a vector A = [1,2,3,4,5], how would you calculate the sum? By adding its elements with each other, right? It's pretty much the same here.

- create a resuting variable and initilize it to 0

 result_sum = 0;

- use the for loop to index through A and add the current element to the above variable

 result_sum = result_sum + A(i);

- once you are done with the for loop calculate mean by diving it with N (just like you've done but outside the loop)

Answer 2

[Dennis]

If the only requirement is to not use sum, i'd like to suggest to use cumsum instead!

    A=cumsum(StrengthVector);
    x=A(end);

As an alternative you could use a loop.

Answer 3

[Matt J]

You can do all sorts of crazy things,

 function Mean = mean_strength(StrengthVector)

    N = numel(StrengthVector);

    if N==1
      Mean = StrengthVector;
    else
     Mean = StrengthVector(1)/N   +  (N-1)/N*mean_strength( StrengthVector(2:end)  );
    end

 end

Answer 4

[Matt J]

x = log( prod(exp(StrengthVector)) );

Answer 5

[Ameer Hamza]

x = 1:10;
s = x*ones(size(x)).'