Add elements in matrix without sum-function

Hello,

How can I sum all the elements in an undefined matrix(the built-in homeworktester puts in its A) without using the sum-function?

This is what I've gotten so far. The result I get is the same element in the matrix multiplied with the numel(A).

function summa = summa_element(A)

[m,n]=size(A)
a=A(m,n)
summa=0;

for i=1:numel(A)
summa= summa + a
end

end

Answer 1

[Guillaume]

"The result I get is the same element in the matrix multiplied with the numel(A)."

Well, yes, you never change a inside the loop. So, you're just adding a, numel(A) times. I'm sure you can figure out what you need to do with a inside the loop.

[Linh Tran]

Thank you for your answer, Guillaume!

I solved it by doing a for-loop in a for-loop for the rows resp. the columns. :)

[Guillaume]

Glad, you solved it. A simpler option would have been to replace

summa = summa + a

by

summa = summa + A(i)

and keep everything else the same (or optionally delete the [m,n]=... and a=... since they're no longer needed)

[Linh Tran]

Ahh! Of course!

I will keep this in mind for further tasks. Thank you!