30-seconds-of-code/snippets/fibonacciCountUntilNum.md

fibonacciCountUntilNum

Returns the number of fibonnacci numbers up to num(0 and num inclusive).

Use a mathematical formula to calculate the number of fibonacci numbers until num.

const fibonacciCountUntilNum = num =>
  Math.ceil(Math.log(num * Math.sqrt(5) + 1/2) / Math.log((Math.sqrt(5)+1)/2));

fibonacciCountUntilNum(10) -> 7