lib-fractions

A PHP library for precision mathematical calculations using rational numbers. This library operates on the rational domain, providing exact decimal representation without the precision loss inherent in floating-point arithmetic.

Features

• Exact Precision: No floating-point rounding errors
• Rational Number Arithmetic: Operations on fractions with significand, denominator, and exponent
• Multiple Input Formats: Create rational numbers from integers, floats, or explicit fraction components
• JSON Serializable: Easy integration with APIs and data storage
• Comprehensive Operations: Addition, subtraction, multiplication, division, and comparison
• Flexible Rounding: Configurable rounding modes when converting from floats

Installation

Install via Composer:

composer require scruoge/lib-fractions

Requirements

• PHP 8.0 or higher

Quick Start

<?php

use Scruoge\Fractions\RationalExp;

// Create rational numbers
$a = RationalExp::fromNumber(2.3);        // 2.3 as exact fraction
$b = RationalExp::create(120, -2);        // 120 * 10^(-2) = 1.2
$c = RationalExp::zero();                 // 0
$d = RationalExp::one();                  // 1

// Perform arithmetic operations
$sum = $a->add($b);                       // 2.3 + 1.2 = 3.5
$difference = $a->sub($b);                // 2.3 - 1.2 = 1.1
$product = $a->mul($b);                   // 2.3 * 1.2 = 2.76
$quotient = $a->div($b);                  // 2.3 / 1.2 = 1.916...

// Convert back to float
echo $sum->toFloat();                     // 3.5

// Check equality
$isEqual = $a->equals($b);                // false

API Reference

Constructor Methods

create(int $significand, int $exponent = 0, int $denominator = 1): RationalExp

Creates a rational number with explicit components.

// Creates 123 * 10^(-2) / 4 = 1.23/4 = 0.3075
$rational = RationalExp::create(123, -2, 4);

fromNumber(int|float $number, int $digits = -1, int $roundMode = PHP_ROUND_HALF_UP): RationalExp

Creates a rational number from an integer or float.

// Automatic precision detection
$auto = RationalExp::fromNumber(1234.2345);

// Fixed precision with rounding
$rounded = RationalExp::fromNumber(1234.2345, 3);             // 3 decimal places
$roundDown = RationalExp::fromNumber(1234.2345, 3, PHP_ROUND_HALF_DOWN);

zero(): RationalExp and one(): RationalExp

Convenience methods for common values.

$zero = RationalExp::zero();    // 0
$one = RationalExp::one();      // 1

Arithmetic Operations

All arithmetic operations return a new RationalExp instance:

$a = RationalExp::fromNumber(2.5);
$b = RationalExp::fromNumber(1.5);

$addition = $a->add($b);        // 4.0
$subtraction = $a->sub($b);     // 1.0
$multiplication = $a->mul($b);  // 3.75
$division = $a->div($b);        // 1.666...

Utility Methods

equals(RationalExp $that): bool

Checks if two rational numbers are equal.

$a = RationalExp::fromNumber(0.1);
$b = RationalExp::fromNumber(0.1);
$isEqual = $a->equals($b);      // true

toFloat(): float

Converts the rational number to a float (may lose precision).

$rational = RationalExp::create(1, 0, 3);
$float = $rational->toFloat();  // 0.3333...

jsonSerialize(): array

Serializes the rational number for JSON encoding.

$rational = RationalExp::create(1, 2, 3);
$json = json_encode($rational);
// {"significand":1,"denominator":3,"exponent":2}

Advanced Usage

Working with Fractions

// Create 3/8
$fraction = RationalExp::create(3, 0, 8);

// Create 1/3 (which cannot be represented exactly as a decimal)
$oneThird = RationalExp::create(1, 0, 3);

Precision Control

When converting from floats, you can control precision and rounding:

$value = 1234.2345;

// Automatic precision (detects significant digits)
$auto = RationalExp::fromNumber($value);

// Fixed precision
$fixed = RationalExp::fromNumber($value, 2);  // 1234.23

// Different rounding modes
$halfUp = RationalExp::fromNumber($value, 2, PHP_ROUND_HALF_UP);    // 1234.23
$halfDown = RationalExp::fromNumber($value, 2, PHP_ROUND_HALF_DOWN); // 1234.23
$up = RationalExp::fromNumber($value, 2, PHP_ROUND_UP);            // 1234.24

Financial Calculations

Perfect for monetary calculations where precision is crucial:

$price = RationalExp::fromNumber(19.99);
$taxRate = RationalExp::fromNumber(0.08);
$quantity = RationalExp::fromNumber(3);

$subtotal = $price->mul($quantity);           // 59.97
$tax = $subtotal->mul($taxRate);              // 4.7976
$total = $subtotal->add($tax);                // 64.7676

// Round to cents for final amount
$finalTotal = RationalExp::fromNumber($total->toFloat(), 2);  // 64.77

Development

Setup

Clone the repository and install dependencies:

git clone https://github.com/scruoge/lib-fractions.git
cd lib-fractions
composer install

Running Tests

composer test
# or
./vendor/bin/phpunit

Code Style

This project uses PHP-CS-Fixer for code formatting:

composer cs-fix
# or
./vendor/bin/php-cs-fixer fix

Project Structure

lib-fractions/
├── src/
│   └── RationalExp.php      # Main rational number class
├── test/
│   └── RationalExpTest.php  # Unit tests
├── composer.json            # Project configuration
├── phpunit.xml             # PHPUnit configuration
└── .php-cs-fixer.dist.php  # Code style configuration

Use Cases

This library is particularly useful for:

• Financial applications where exact decimal representation is required
• Scientific calculations requiring rational number precision
• Data processing where floating-point errors must be avoided
• Mathematical applications working with fractions and ratios

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes
4. Run tests (composer test)
5. Fix code style (composer cs-fix)
6. Commit your changes (git commit -m 'Add amazing feature')
7. Push to the branch (git push origin feature/amazing-feature)
8. Open a Pull Request

Please ensure all tests pass and follow the existing code style.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Author

Sergey N. Kruk - scruoge@gmail.com

---

For more examples and detailed documentation, please refer to the test files in the test/ directory.