Simple question about functions

function nFib = fib(n)

a = (1 + sqrt(sym(5)))/2;
nFib = (a^n)-((-a)^(-n)) / sqrt(sym(5)) ;

end

*The output for this function when n=3 is

fib(3)

ans =

5^(1/2)/(5*(5^(1/2)/2 + 1/2)^3) + (5^(1/2)/2 + 1/2)^3

Why isn't the answer showing the number but just the entire function itself? And how can I solve this problem to show the actual answer(in number)? Thank you!

Answer 1

[Andrei Bobrov]

function nFib = fib(n)

      a = (1 + sqrt(5))/2;
      nFib = a^n-(-a)^(-n) / sqrt(5) ;

end

[Danny C]

Now it's working. Would you mind telling me what was wrong in my function?

[Andrei Bobrov]

I replaced the symbolic expression (sym(5)) to a value of integer 5.