Rust高性能数值计算库fastnum的使用

已提供的示例代码

use fastnum::*;

fn main() {
    const ZERO: UD256 = udec256!(0);
    const ONE: UD256 = udec256!(1.0);

    let a = udec256!(12345);
    let b = udec256!(67.89);
    
    // 加法
    let sum = a + b;
    println!("Sum: {}", sum);
    
    // 减法
    let diff = a - b;
    println!("Difference: {}", diff);
    
    // 乘法
    let product = a * b;
    println!("Product: {}", product);
    
    // 除法
    let quotient = a / b;
    println!("Quotient: {}", quotient);
    
    // 平方根
    let sqrt = a.sqrt();
    println!("Square root: {}", sqrt);
}

完整示例代码

use fastnum::*;

fn main() {
    // 定义常量
    const PI: D128 = dec128!(3.14159265358979323846264338327950288);
    const E: D128 = dec128!(2.71828182845904523536028747135266249);
    
    // 创建变量
    let radius = dec128!(5.0);
    let height = dec128!(10.0);
    
    // 计算圆柱体体积: V = πr²h
    let volume = PI * radius.pow(2) * height;
    println!("圆柱体体积: {}", volume);
    
    // 计算复利
    let principal = dec128!(1000.0);
    let rate = dec128!(0.05);  // 5%利率
    let years = dec128!(10.0);
    let compound_interest = principal * (D128::one() + rate).pow(years) - principal;
    println!("10年后的复利: {}", compound_interest);
    
    // 三角函数示例
    let angle = dec128!(45.0);
    let radians = angle.to_radians();
    println!("sin(45°) = {}", radians.sin());
    println!("cos(45°) = {}", radians.cos());
    println!("tan(45°) = {}", radians.tan());
    
    // 对数计算
    println!("ln(E) = {}", E.ln());
    println!("log10(100) = {}", dec128!(100.0).log10());
    
    // 特殊值处理
    let inf = D128::INFINITY;
    let nan = D128::NAN;
    println!("Infinity + 1 = {}", inf + D128::one());
    println!("NaN == NaN? {}", nan == nan);  // false
}

补充完整示例

以下是一个更完整的金融计算示例，展示了fastnum在金融领域的应用：

use fastnum::*;

fn main() {
    // 金融计算示例 - 期权定价
    let s = dec128!(100.0);  // 标的资产价格
    let k = dec128!(105.0);  // 行权价
    let r = dec128!(0.05);   // 无风险利率
    let t = dec128!(1.0);    // 到期时间(年)
    let sigma = dec128!(0.2); // 波动率
    
    // 计算看涨期权价格(Black-Scholes模型)
    let call_price = black_scholes_call(s, k, r, t, sigma);
    println!("看涨期权价格: {}", call_price);
    
    // 计算贷款还款计划
    let loan_amount = dec128!(100000.0);
    let annual_rate = dec128!(0.06); // 6%年利率
    let years = dec128!(30.0);
    calculate_loan_payment(loan_amount, annual_rate, years);
}

// Black-Scholes看涨期权定价公式
fn black_scholes_call(s: D128, k: D128, r: D128, t: D128, sigma: D128) -> D128 {
    let sqrt_t = t.sqrt();
    let d1 = ((s / k).ln() + (r + sigma.pow(2) / dec128!(2.0)) * t) / (sigma * sqrt_t);
    let d2 = d1 - sigma * sqrt_t;
    
    // 使用标准正态分布函数(这里简化处理，实际应用中需要实现)
    let nd1 = norm_cdf(d1);
    let nd2 = norm_cdf(d2);
    
    s * nd1 - k * (-r * t).exp() * nd2
}

// 简化版标准正态分布CDF
fn norm_cdf(x: D128) -> D128 {
    // 实际应用中应该实现完整的近似计算
    if x > dec128!(0.0) {
        dec128!(0.5)
    } else {
        dec128!(0.5)
    }
}

// 计算等额本息贷款还款计划
fn calculate_loan_payment(loan_amount: D128, annual_rate: D128, years: D128) {
    let monthly_rate = annual_rate / dec128!(12.0);
    let months = years * dec128!(12.0);
    
    // 每月还款额公式: P * r * (1+r)^n / ((1+r)^n - 1)
    let monthly_payment = loan_amount * monthly_rate * 
        (D128::one() + monthly_rate).pow(months) / 
        ((D128::one() + monthly_rate).pow(months) - D128::one());
    
    println!("贷款金额: {}", loan_amount);
    println!("年利率: {}%", annual_rate * dec128!(100.0));
    println!("贷款期限: {}年", years);
    println!("每月还款额: {}", monthly_payment);
    
    // 计算总还款额和总利息
    let total_payment = monthly_payment * months;
    let total_interest = total_payment - loan_amount;
    println!("总还款额: {}", total_payment);
    println!("总利息: {}", total_interest);
}