MATLAB: Output argument ‘answers’ (and maybe others) not assigned during call to “…”

errorfibonaccinot assignedrecursionseries

I am trying to create a function that sums up all the values of the fibonacci series using only recursion, but I keep getting this error message…
Output argument "answer" (and maybe others) not
assigned during call to "sum_of_fibo>fibo".
Error in sum_of_fibo (line 2)
    summa = sum(fibo(n:-1:0));
Here's my code…can someone help?
function summa = sum_of_fibo(n)
    summa = sum(fibo(n:-1:0));
end 
function answer = fibo(n)
if n == 0
    answer = 1;
elseif n == 1
    answer = 1;
elseif n > 1
    answer = fibo(n-1) + fibo(n-2);
end
end

Best Answer

If you pass in something like -1 or 0.4, answer will never get set to anything. You should set it to something, even if it's null, to avoid that error. Better yet, make an "else" for your if to handle cases where you're passing in values that are not positive integers or zero.
function answer = fibo(n)
answer = []; % empty
if n == 0
    answer = 1;
elseif n == 1
    answer = 1;
elseif n > 1
    answer = fibo(n-1) + fibo(n-2);
end
end
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