投资 ROI/IRR/NPV

复制import numpy as np
from numpy_financial import irr, npv

# 现金流：第0年投入-1000，第1-5年每年回收300
cashflows = [-1000, 300, 300, 300, 300, 300]

# 净现值（折现率10%）
npv_value = npv(0.10, cashflows)
print(f"NPV = {npv_value:.2f}")  # NPV = 137.24

# 内部收益率
irr_value = irr(cashflows)
print(f"IRR = {irr_value:.4f}")  # IRR = 0.1524 (15.24%)

# 投资回报率（简单ROI）
total_return = sum(cashflows[1:])
roi = (total_return - abs(cashflows[0])) / abs(cashflows[0])
print(f"ROI = {roi:.2%}")  # ROI = 50.00%

复制package main

import (
	"fmt"
	"math"
)

// NPV 计算净现值
func NPV(rate float64, cashflows []float64) float64 {
	var npv float64
	for i, cf := range cashflows {
		npv += cf / math.Pow(1+rate, float64(i))
	}
	return npv
}

// IRR 使用牛顿法计算内部收益率
func IRR(cashflows []float64) float64 {
	guess := 0.1
	for i := 0; i < 1000; i++ {
		npv := NPV(guess, cashflows)
		// 导数近似
		derivative := (NPV(guess+0.0001, cashflows) - npv) / 0.0001
		if math.Abs(derivative) < 1e-12 {
			break
		}
		guess -= npv / derivative
		if math.Abs(npv) < 1e-6 {
			break
		}
	}
	return guess
}

func main() {
	cashflows := []float64{-1000, 300, 300, 300, 300, 300}

	// 净现值（折现率10%）
	fmt.Printf("NPV = %.2f\n", NPV(0.10, cashflows)) // 137.24

	// 内部收益率
	fmt.Printf("IRR = %.4f\n", IRR(cashflows)) // 0.1524

	// 简单ROI
	totalReturn := 0.0
	for _, cf := range cashflows[1:] {
		totalReturn += cf
	}
	roi := (totalReturn - math.Abs(cashflows[0])) / math.Abs(cashflows[0])
	fmt.Printf("ROI = %.2f%%\n", roi*100) // 50.00%
}

复制// 净现值计算
function npv(rate, cashflows) {
  return cashflows.reduce((acc, cf, i) => acc + cf / Math.pow(1 + rate, i), 0);
}

// 内部收益率（牛顿法）
function irr(cashflows) {
  let guess = 0.1;
  for (let i = 0; i < 1000; i++) {
    const npvVal = npv(guess, cashflows);
    const derivative = (npv(guess + 0.0001, cashflows) - npvVal) / 0.0001;
    if (Math.abs(derivative) < 1e-12) break;
    guess -= npvVal / derivative;
    if (Math.abs(npvVal) < 1e-6) break;
  }
  return guess;
}

const cashflows = [-1000, 300, 300, 300, 300, 300];

// 净现值（折现率10%）
console.log(`NPV = ${npv(0.10, cashflows).toFixed(2)}`); // 137.24

// 内部收益率
console.log(`IRR = ${irr(cashflows).toFixed(4)}`); // 0.1524

// 简单ROI
const totalReturn = cashflows.slice(1).reduce((a, b) => a + b, 0);
const roi = (totalReturn - Math.abs(cashflows[0])) / Math.abs(cashflows[0]);
console.log(`ROI = ${(roi * 100).toFixed(2)}%`); // 50.00%