# [erlang-questions] is this a well written function

Roelof Wobben r.wobben@REDACTED
Mon Feb 9 10:38:48 CET 2015

```Hello,

I tried to solve the exercise where I have to calculate the outcome of 1
... n

So I have this :

-module(sum_recursion).

-export([sum/1]).

% when the number is zero the outcome will also be zero
sum(0) ->
0;

% when the output is a number higher then 0 , the acc function will be
called.
sum(Number) -> sum_acc(Number, 0, 0 ).

% when the numbers are equal then the end is reached and the last item
is added to the acc variable,
% the acc variable hold the value of the sum as it is calculated
sum_acc(Endnumber,  Endnumber, Acc) ->
Acc + Endnumber ;

% when the numbers are not equal then the end is not reached so the
function is again called with the original number,
% the loop is increased by 1 and the acc function hold the value of the
sum as it is calculated.
sum_acc(Endnumber, Number, Acc) ->
sum_acc(Endnumber, Number + 1, Acc + Number).

Now I wonder if this is well written Erlang ?

Roelof

```