Present Value and Future Value

/**
 * Fintech Math Bootcamp · Lesson 013 of 120
 * Present Value and Future Value
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: Comparing money on two different dates
 * Rule:     PV = FV/(1+r)ⁿ
 *
 * Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/present-future-value/
 * Free course:    https://courses.thefintechbuilder.com
 * Synthetic teaching example, not financial advice or a production library.
 */

export function lesson013() {
  const future = 1210, rate = 0.10, years = 2;
  const present = future / (1 + rate) ** years;
  const reconstructed = present * (1 + rate) ** years;
  const result = {present, reconstructed};
  return result;
}

export const checkedResult = {"present":999.9999999999999,"reconstructed":1210};

// Run this file directly: npx tsx lessons/02-financial-arithmetic-time-value-and-returns/013-present-value-and-future-value.ts
if (process.argv[1] && import.meta.url.endsWith(process.argv[1].replace(/\\/g, "/").split("/").pop()!)) {
  console.log(JSON.stringify(lesson013(), null, 2));
}

"""
Fintech Math Bootcamp · Lesson 013 of 120
Present Value and Future Value
Module 02: Financial Arithmetic, Time Value, and Returns

Scenario: Comparing money on two different dates
Rule:     PV = FV/(1+r)ⁿ

Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?

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

Run it: python main.py
"""

import json


def lesson013() -> dict:
    future, rate, years = 1210, 0.10, 2
    present = future / (1 + rate) ** years
    reconstructed = present * (1 + rate) ** years
    result = {"present": present, "reconstructed": reconstructed}
    return result


if __name__ == "__main__":
    print(json.dumps(lesson013(), indent=2))

/**
 * Fintech Math Bootcamp · Lesson 013 of 120
 * Present Value and Future Value
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: Comparing money on two different dates
 * Rule:     PV = FV/(1+r)^n
 *
 * Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/present-future-value/
 * 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 PresentValue {
        final double present;
        final double reconstructed;

        PresentValue(double present, double reconstructed) {
            this.present = present;
            this.reconstructed = reconstructed;
        }
    }

    static PresentValue lesson013() {
        double future = 1210, rate = 0.10, years = 2;
        double present = future / Math.pow(1 + rate, years);
        double reconstructed = present * Math.pow(1 + rate, years);
        PresentValue result = new PresentValue(present, reconstructed);
        return result;
    }

    public static void main(String[] args) {
        PresentValue result = lesson013();
        System.out.println(object(
            "present", num(result.present),
            "reconstructed", num(result.reconstructed)));
    }

    // 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 013 of 120
// Present Value and Future Value
// Module 02: Financial Arithmetic, Time Value, and Returns
//
// Scenario: Comparing money on two different dates
// Rule:     PV = FV/(1+r)ⁿ
//
// Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?
//
// Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/present-future-value/
// 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"
	"fmt"
	"math"
)

type PresentValue struct {
	Present       float64 `json:"present"`
	Reconstructed float64 `json:"reconstructed"`
}

func lesson013() PresentValue {
	future, rate, years := 1210.0, 0.10, 2.0
	present := future / math.Pow(1+rate, years)
	reconstructed := present * math.Pow(1+rate, years)
	result := PresentValue{Present: present, Reconstructed: reconstructed}
	return result
}

func main() {
	printJSON(lesson013())
}

// 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 013 of 120
 * Present Value and Future Value
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: Comparing money on two different dates
 * Rule:     PV = FV/(1+r)ⁿ
 *
 * Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/present-future-value/
 * 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 <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 PresentValue {
    double present;
    double reconstructed;
};

PresentValue lesson013() {
    const double future = 1210, rate = 0.10, years = 2;
    const double present = future / std::pow(1 + rate, years);
    const double reconstructed = present * std::pow(1 + rate, years);
    const PresentValue result{present, reconstructed};
    return result;
}

int main() {
    const PresentValue result = lesson013();
    std::cout << object({
        {"present", num(result.present)},
        {"reconstructed", num(result.reconstructed)}
    }) << "\n";
}

//! Fintech Math Bootcamp · Lesson 013 of 120
//! Present Value and Future Value
//! Module 02: Financial Arithmetic, Time Value, and Returns
//!
//! Scenario: Comparing money on two different dates
//! Rule:     PV = FV/(1+r)ⁿ
//!
//! Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?
//!
//! Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/present-future-value/
//! Free course:    https://courses.thefintechbuilder.com
//! Synthetic teaching example, not financial advice or a production library.
//!
//! Run it: rustc main.rs && ./main

struct PresentValue {
    present: f64,
    reconstructed: f64,
}

fn lesson013() -> PresentValue {
    let (future, rate, years): (f64, f64, f64) = (1210.0, 0.10, 2.0);
    let present = future / (1.0 + rate).powf(years);
    let reconstructed = present * (1.0 + rate).powf(years);
    let result = PresentValue { present, reconstructed };
    result
}

fn main() {
    let result = lesson013();
    println!(
        "{}",
        object(&[
            ("present", num(result.present)),
            ("reconstructed", num(result.reconstructed)),
        ])
    );
}

/// 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 013 of 120
 * Present Value and Future Value
 * Module 02: Financial Arithmetic, Time Value, and Returns
 *
 * Scenario: Comparing money on two different dates
 * Rule:     PV = FV/(1+r)ⁿ
 *
 * Try it:   What happens to PV when the positive discount rate rises, holding FV fixed?
 *
 * Lesson article: https://thefintechbuilder.com/financial-mathematics-statistics-and-data-foundations/financial-arithmetic-time-value-and-returns/present-future-value/
 * 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(Lesson013(), jsonOptions));

static PresentValue Lesson013()
{
    double future = 1210, rate = 0.10, years = 2;
    var present = future / Math.Pow(1 + rate, years);
    var reconstructed = present * Math.Pow(1 + rate, years);
    var result = new PresentValue(present, reconstructed);
    return result;
}

record PresentValue(double Present, double Reconstructed);