Code shared from the Rust Playground

playground.rs

use std::f64::consts::PI;

fn main() {
    let mut sum = 0.0;
    let mut term = 1.0;
    let mut k = 0;

    loop {
        sum += term;
        k += 1;
        term *= PI * PI.ln() / k as f64;

        if term.abs() < 1e-15 {
            break;
        }
    }

    println!("Pi to the power of Pi: {}", sum);
}