Matlab language to C

Why this functions doesn't work on matlab coder

function [S,er]=somm1(n)
%n est le nombre de terme de la serie
S=0;
for x = 1:n
S=S+4*(-1)^(x-1)*(1/(2*x-1));
er=abs(S-pi)/pi;
end

It is saying that 'er' is not assigned on some exucution path.

How can I resolve this problem? Thank you

Answer 1

[Guillaume]

If n is smaller than 1, the loop will not execute, hence er will never get created. Either assign a default value to er before the loop e.g.

er = nan;
for ...

or, if matlab coder supports it (I don't have it so don't know), issue an error before the loop if n is not valid:

if n < 1 
   error('nombre de termes doit etre au moins 1');
end
for ...