# Sum of array as an others array value

#1

Hi everyone, im new and this is my first question here.
I’m wondering why this is not possible:

If i Type:

``````A=[1.0, 2.0, 3.0, 4.0, 5.0];
B=zeros(5);
``````

and then

``````sum(A)=B[1]
``````

i get the error Message:

``````error in method definition: function Base.sum must be explicitly imported to be extended
``````

Why is this ?

Typing

``````typeof(sum(A))
``````

its Float64 like the elements of B?

also

``````sum(A[1:3])=B[1]
``````

does not work , but now with the error mesasage:

``````syntax: "A[1:3]" is not a valid function argument name
``````

Thanks

#2

You can’t extend a `Base` method without importing it first. `sum(A) = B[1]` is a method definition, this is entirely different from just typing `sum(A)`, because `=` is an assignment operator.

`sum(A[1:3])=B[1]` is invalid syntax.

#3

Welcome!

Perhaps it would be useful if you explain what you’re trying to do, or what you expect to happen?

Also, to show code please use backticks (`) or triple-backticks(```) (I took the liberty of editing your post).

#4

It is not clear from your question what you really want to do or what is the expected behavior that you assumed. Perhaps you mean to do this?

``````A = [1.0, 2.0, 3.0, 4.0, 5.0]
B = zeros(5)

B[1] = sum(A)
B[1] = sum(A[1:3])
``````

#5

Seif_Shebl, you are right, that is what i really wanted t do…and it works fine.
what a stupid mistake of mine…
Thanks a lot for the answers to everybody.