025 1000-digit Fibonacci number -- v3.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# https://github.com/trizen

# What is the index of the first term in the Fibonacci sequence to contain 1000 digits?

# https://projecteuler.net/problem=25

# Runtime: 0.302s

func fibonacci_inverse_approx(n) {
    log(n * sqrt(5), Num.phi)
}

say ceil(fibonacci_inverse_approx(10**(1000 - 1)))