Test if a number is fibonacci

Question

I know how to make the list of the Fibonacci numbers, but i don\'t know how can i test if a given number belongs to the fibonacci list - one way that comes in mind is genera

Answer 1

This is my solution I'm not sure if it benchmarks. I hope this helps!

def is_fibonacci?(i)
  a,b=0,1
    until b >= i
        a,b=b,a+b
        return true if b == i
    end
end

what a,b=b,a+b is doing

 0, 1 = 1, 0 +1
 1, 1 = 1, 1 + 1
 1, 2 = 2, 1 + 2
 2, 3 = 3, 2 + 3

fib1 = fib2
fib2 = fib1 + fib2