Math Constants

Mathematical constants ใน Rust Standard Library

PI และ TAU

use std::f64::consts::*;

fn main() {
    // ============================================
    // Circle Constants
    // ============================================

    println!("=== Circle Constants ===");
    println!("PI:      {}", PI);
    println!("TAU:     {} (2π)", TAU);
    println!("FRAC_PI_2: {} (π/2)", FRAC_PI_2);
    println!("FRAC_PI_3: {} (π/3)", FRAC_PI_3);
    println!("FRAC_PI_4: {} (π/4)", FRAC_PI_4);
    println!("FRAC_PI_6: {} (π/6)", FRAC_PI_6);
    println!("FRAC_PI_8: {} (π/8)", FRAC_PI_8);

    // ============================================
    // Circle calculations
    // ============================================

    let radius = 5.0;
    let circumference = TAU * radius;
    let area = PI * radius * radius;

    println!("\nCircle with r={}:", radius);
    println!("Circumference: {:.2}", circumference);
    println!("Area: {:.2}", area);

    // ============================================
    // Angle conversions
    // ============================================

    let degrees = 180.0;
    let radians = degrees * PI / 180.0;
    println!("\n{}° = {} radians", degrees, radians);

    let radians = FRAC_PI_4;
    let degrees = radians * 180.0 / PI;
    println!("π/4 radians = {}°", degrees);
}