Simple Return

/**
 * Fintech Math Bootcamp · Lesson 016 of 120
 * Simple Return
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: A dividend can change the answer even when the price is known
 * Rule:     R = (P₁ − P₀ + cash)/P₀
 *
 * Try it:   Could adding cash to an already total-return-adjusted series double count?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
 * Free course:    https://courses.thefintechbuilder.com
 * Synthetic teaching example, not financial advice or a production library.
 */

export function lesson016() {
  const start = 100, end = 108, cash = 2;
  if (start <= 0) throw new Error("Positive base required");
  const priceReturn = (end - start) / start;
  const totalReturn = (end - start + cash) / start;
  const result = {priceReturn, totalReturn};
  return result;
}

export const checkedResult = {"priceReturn":0.08,"totalReturn":0.1};

// Run this file directly: npx tsx lessons/02-financial-arithmetic-time-value-and-returns/016-simple-return.ts
if (process.argv[1] && import.meta.url.endsWith(process.argv[1].replace(/\\/g, "/").split("/").pop()!)) {
  console.log(JSON.stringify(lesson016(), null, 2));
}

"""
Fintech Math Bootcamp · Lesson 016 of 120
Simple Return
Module 02: Financial Arithmetic, Time Value, and Returns

Scenario: A dividend can change the answer even when the price is known
Rule:     R = (P₁ − P₀ + cash)/P₀

Try it:   Could adding cash to an already total-return-adjusted series double count?

Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
Free course:    https://courses.thefintechbuilder.com
Synthetic teaching example, not financial advice or a production library.

Run it: python main.py
"""

import json


def lesson016() -> dict:
    start, end, cash = 100, 108, 2
    if start <= 0:
        raise ValueError("Positive base required")
    price_return = (end - start) / start
    total_return = (end - start + cash) / start
    result = {"priceReturn": price_return, "totalReturn": total_return}
    return result


if __name__ == "__main__":
    print(json.dumps(lesson016(), indent=2))

/**
 * Fintech Math Bootcamp · Lesson 016 of 120
 * Simple Return
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: A dividend can change the answer even when the price is known
 * Rule:     R = (P1 − P0 + cash)/P0
 *
 * Try it:   Could adding cash to an already total-return-adjusted series double count?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
 * Free course:    https://courses.thefintechbuilder.com
 * Synthetic teaching example, not financial advice or a production library.
 *
 * Run it: javac Main.java && java Main
 */

public class Main {
    static final class HoldingReturn {
        final double priceReturn;
        final double totalReturn;

        HoldingReturn(double priceReturn, double totalReturn) {
            this.priceReturn = priceReturn;
            this.totalReturn = totalReturn;
        }
    }

    static HoldingReturn lesson016() {
        double start = 100, end = 108, cash = 2;
        if (start <= 0) throw new IllegalArgumentException("Positive base required");
        double priceReturn = (end - start) / start;
        double totalReturn = (end - start + cash) / start;
        HoldingReturn result = new HoldingReturn(priceReturn, totalReturn);
        return result;
    }

    public static void main(String[] args) {
        HoldingReturn result = lesson016();
        System.out.println(object(
            "priceReturn", num(result.priceReturn),
            "totalReturn", num(result.totalReturn)));
    }

    // Formats a double the way JSON.stringify does: whole numbers without ".0", null for NaN or infinity.
    static String num(double x) {
        if (Double.isNaN(x) || Double.isInfinite(x)) return "null";
        if (x == Math.rint(x) && Math.abs(x) < 1e15) return String.valueOf((long) x);
        return String.valueOf(x);
    }

    static String quote(String text) {
        return "\"" + text.replace("\\", "\\\\").replace("\"", "\\\"") + "\"";
    }

    // Indents an already formatted JSON value by one level.
    static String nested(String json) {
        return json.replace("\n", "\n  ");
    }

    static String object(String... keysAndValues) {
        if (keysAndValues.length == 0) return "{}";
        StringBuilder out = new StringBuilder("{");
        for (int i = 0; i < keysAndValues.length; i += 2) {
            out.append(i == 0 ? "\n  " : ",\n  ")
               .append(quote(keysAndValues[i])).append(": ").append(nested(keysAndValues[i + 1]));
        }
        return out.append("\n}").toString();
    }
}

// Fintech Math Bootcamp · Lesson 016 of 120
// Simple Return
// Module 02: Financial Arithmetic, Time Value, and Returns
//
// Scenario: A dividend can change the answer even when the price is known
// Rule:     R = (P₁ − P₀ + cash)/P₀
//
// Try it:   Could adding cash to an already total-return-adjusted series double count?
//
// Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
// Free course:    https://courses.thefintechbuilder.com
// Synthetic teaching example, not financial advice or a production library.
//
// Run it: go run main.go

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
)

type HoldingReturn struct {
	PriceReturn float64 `json:"priceReturn"`
	TotalReturn float64 `json:"totalReturn"`
}

func lesson016() (HoldingReturn, error) {
	start, end, cash := 100.0, 108.0, 2.0
	if start <= 0 {
		return HoldingReturn{}, errors.New("Positive base required")
	}
	priceReturn := (end - start) / start
	totalReturn := (end - start + cash) / start
	result := HoldingReturn{PriceReturn: priceReturn, TotalReturn: totalReturn}
	return result, nil
}

func main() {
	result, err := lesson016()
	if err != nil {
		fmt.Fprintln(os.Stderr, "Error:", err)
		os.Exit(1)
	}
	printJSON(result)
}

// printJSON prints a value as JSON indented with two spaces, like JSON.stringify(value, null, 2).
func printJSON(value any) {
	out, err := json.MarshalIndent(value, "", "  ")
	if err != nil {
		panic(err)
	}
	fmt.Println(string(out))
}

/**
 * Fintech Math Bootcamp · Lesson 016 of 120
 * Simple Return
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: A dividend can change the answer even when the price is known
 * Rule:     R = (P₁ − P₀ + cash)/P₀
 *
 * Try it:   Could adding cash to an already total-return-adjusted series double count?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
 * Free course:    https://courses.thefintechbuilder.com
 * Synthetic teaching example, not financial advice or a production library.
 *
 * Run it: g++ -std=c++17 -o main main.cpp && ./main
 */

#include <charconv>
#include <cmath>
#include <iostream>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>

// Formats a double the way JSON.stringify does: shortest round-trip form, null for NaN or infinity.
std::string num(double x) {
    if (!std::isfinite(x)) return "null";
    char buffer[32];
    auto [end, error] = std::to_chars(buffer, buffer + sizeof buffer, x);
    (void)error;
    return std::string(buffer, end);
}

std::string quote(const std::string& text) {
    std::string out = "\"";
    for (char c : text) {
        if (c == '"' || c == '\\') out += '\\';
        out += c;
    }
    return out + "\"";
}

// Indents an already formatted JSON value by one level.
std::string nested(const std::string& json) {
    std::string out;
    for (char c : json) {
        out += c;
        if (c == '\n') out += "  ";
    }
    return out;
}

std::string object(const std::vector<std::pair<std::string, std::string>>& fields) {
    if (fields.empty()) return "{}";
    std::string out = "{";
    for (std::size_t i = 0; i < fields.size(); ++i) {
        out += i == 0 ? "\n  " : ",\n  ";
        out += quote(fields[i].first) + ": " + nested(fields[i].second);
    }
    return out + "\n}";
}

struct HoldingReturn {
    double priceReturn;
    double totalReturn;
};

HoldingReturn lesson016() {
    const double start = 100, end = 108, cash = 2;
    if (start <= 0) throw std::invalid_argument("Positive base required");
    const double priceReturn = (end - start) / start;
    const double totalReturn = (end - start + cash) / start;
    const HoldingReturn result{priceReturn, totalReturn};
    return result;
}

int main() {
    const HoldingReturn result = lesson016();
    std::cout << object({
        {"priceReturn", num(result.priceReturn)},
        {"totalReturn", num(result.totalReturn)}
    }) << "\n";
}

//! Fintech Math Bootcamp · Lesson 016 of 120
//! Simple Return
//! Module 02: Financial Arithmetic, Time Value, and Returns
//!
//! Scenario: A dividend can change the answer even when the price is known
//! Rule:     R = (P₁ − P₀ + cash)/P₀
//!
//! Try it:   Could adding cash to an already total-return-adjusted series double count?
//!
//! Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
//! Free course:    https://courses.thefintechbuilder.com
//! Synthetic teaching example, not financial advice or a production library.
//!
//! Run it: rustc main.rs && ./main

struct HoldingReturn {
    price_return: f64,
    total_return: f64,
}

fn lesson016() -> Result<HoldingReturn, String> {
    let (start, end, cash): (f64, f64, f64) = (100.0, 108.0, 2.0);
    if start <= 0.0 {
        return Err("Positive base required".to_string());
    }
    let price_return = (end - start) / start;
    let total_return = (end - start + cash) / start;
    let result = HoldingReturn { price_return, total_return };
    Ok(result)
}

fn main() {
    match lesson016() {
        Ok(result) => println!("{}", object(&[
            ("priceReturn", num(result.price_return)),
            ("totalReturn", num(result.total_return)),
        ])),
        Err(message) => {
            eprintln!("Error: {}", message);
            std::process::exit(1);
        }
    }
}

/// Formats a number the way JSON.stringify does: shortest round-trip form, null for NaN or infinity.
fn num(x: f64) -> String {
    if x.is_finite() {
        format!("{}", x)
    } else {
        "null".to_string()
    }
}

fn quote(text: &str) -> String {
    format!("\"{}\"", text.replace('\\', "\\\\").replace('"', "\\\""))
}

/// Indents an already formatted JSON value by one level.
fn nested(json: &str) -> String {
    json.replace('\n', "\n  ")
}

fn object(fields: &[(&str, String)]) -> String {
    if fields.is_empty() {
        return "{}".to_string();
    }
    let lines: Vec<String> = fields
        .iter()
        .map(|(key, value)| format!("  {}: {}", quote(key), nested(value)))
        .collect();
    format!("{{\n{}\n}}", lines.join(",\n"))
}

/**
 * Fintech Math Bootcamp · Lesson 016 of 120
 * Simple Return
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: A dividend can change the answer even when the price is known
 * Rule:     R = (P₁ − P₀ + cash)/P₀
 *
 * Try it:   Could adding cash to an already total-return-adjusted series double count?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/simple-return/
 * Free course:    https://courses.thefintechbuilder.com
 * Synthetic teaching example, not financial advice or a production library.
 *
 * Run it: dotnet run  (inside a console project that holds this Program.cs)
 */

using System.Text.Json;

var jsonOptions = new JsonSerializerOptions { WriteIndented = true, PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
Console.WriteLine(JsonSerializer.Serialize(Lesson016(), jsonOptions));

static HoldingReturn Lesson016()
{
    double start = 100, end = 108, cash = 2;
    if (start <= 0) throw new ArgumentException("Positive base required");
    var priceReturn = (end - start) / start;
    var totalReturn = (end - start + cash) / start;
    var result = new HoldingReturn(priceReturn, totalReturn);
    return result;
}

record HoldingReturn(double PriceReturn, double TotalReturn);