how to use sum?

I am trying to use sum but with no success!

For example:

n=1:20;
sum(n./2.^n)

or:

n=20;
k=1:n;
sum(k);

but neither works!Am I missing sth here?

Thanks!

[Jan]

"Neither works" is not a good description of the problem. Better post the error message of explain the difference between the results and your expectations.

Answer 1

[Azzi Abdelmalek]

%They both work fine

%What is your error message?

%Try

clear sum
n=1:20;
sum(n./2.^n)

Mybe sum is used as a variable in your code

[George]

Ok!It wanted clear all!Maybe it messed up with something!!And I was going crazy!

[Jan]

No, Georg, not clear all, but clear sum. See Answers: avoid clear all. But instead of clearing variables, it is much better to avoid using the names of built-in functions as names of variables.