README

A PHP library to work with arbitrary precision numbers.

Installation

This library is installable via Composer:

composer require brick/math

Requirements

This library requires PHP 8.2 or later.

For PHP 8.1 compatibility, you can use version 0.13. For PHP 8.0, you can use version 0.11. For PHP 7.4, you can use version 0.10. For PHP 7.1, 7.2 & 7.3, you can use version 0.9. Note that PHP versions < 8.1 are EOL and not supported anymore. If you're still using one of these PHP versions, you should consider upgrading as soon as possible.

Although the library can work seamlessly on any PHP installation, it is highly recommended that you install the GMP or BCMath extension to speed up calculations. The fastest available calculator implementation will be automatically selected at runtime.

Project status & release process

While this library is still under development, it is well tested and considered stable enough to use in production environments.

The current releases are numbered 0.x.y. When a non-breaking change is introduced (adding new methods, optimizing existing code, etc.), y is incremented.

When a breaking change is introduced, a new 0.x version cycle is always started.

It is therefore safe to lock your project to a given release cycle, such as ^0.17.

If you need to upgrade to a newer release cycle, check the release history for a list of changes introduced by each further 0.x.0 version.

Package contents

This library provides the following public classes in the Brick\Math namespace:

• BigNumber: base class for BigInteger, BigDecimal and BigRational
• BigInteger: represents an arbitrary-precision integer number.
• BigDecimal: represents an arbitrary-precision decimal number.
• BigRational: represents an arbitrary-precision rational number (fraction), always reduced to lowest terms.
• RoundingMode: enum representing all available rounding modes.

And exceptions in the Brick\Math\Exception namespace.

Overview

Instantiation

The constructors of the classes are not public, you must use a factory method to obtain an instance.

All classes provide an of() factory method that accepts any of the following types:

• BigNumber instances
• int numbers
• string representations of integer, decimal and rational numbers

Example:

BigInteger::of(123546);
BigInteger::of('9999999999999999999999999999999999999999999');

BigDecimal::of('9.99999999999999999999999999999999999999999999');

BigRational::of('2/3');

Note that all of() methods accept all the representations above, as long as it can be safely converted to the current type:

BigInteger::of('1.00'); // 1
BigInteger::of('1.01'); // RoundingNecessaryException

BigDecimal::of('1/8'); // 0.125
BigDecimal::of('1/3'); // RoundingNecessaryException

BigRational::of('1.1'); // 11/10
BigRational::of('1.15'); // 23/20 (reduced to lowest terms)

Note

The of() factory method does not accept float values, because casting a float to string can be lossy. To convert a float to a BigDecimal, use one of the dedicated methods:

// Exact IEEE-754 representation — the value the float actually holds:
BigDecimal::fromFloatExact(0.1); // 0.1000000000000000055511151231257827021181583404541015625

// Shortest decimal that round-trips back to the same float:
BigDecimal::fromFloatShortest(0.1); // 0.1

Immutability & chaining

The BigInteger, BigDecimal and BigRational classes are immutable: their value never changes, so that they can be safely passed around. All methods that return a BigInteger, BigDecimal or BigRational return a new object, leaving the original object unaffected:

$ten = BigInteger::of(10);

echo $ten->plus(5); // 15
echo $ten->multipliedBy(3); // 30

The methods can be chained for better readability:

echo BigInteger::of(10)->plus(5)->multipliedBy(3); // 45

Parameter types

All methods that accept a number: plus(), minus(), multipliedBy(), etc. accept the same types as of(). For example, given the following number:

$integer = BigInteger::of(123);

The following lines are equivalent:

$integer->multipliedBy(123);
$integer->multipliedBy('123');
$integer->multipliedBy($integer);

Just like of(), other types of BigNumber are acceptable, as long as they can be safely converted to the current type:

echo BigInteger::of(2)->multipliedBy(BigDecimal::of('2.0')); // 4
echo BigInteger::of(2)->multipliedBy(BigDecimal::of('2.5')); // RoundingNecessaryException
echo BigDecimal::of(2.5)->multipliedBy(BigInteger::of(2)); // 5.0

Division & rounding

BigInteger

By default, dividing a BigInteger returns the exact result of the division, or throws an exception if the remainder of the division is not zero:

echo BigInteger::of(999)->dividedBy(3); // 333
echo BigInteger::of(1000)->dividedBy(3); // RoundingNecessaryException

You can pass an optional rounding mode to round the result, if necessary:

echo BigInteger::of(1000)->dividedBy(3, RoundingMode::Down); // 333
echo BigInteger::of(1000)->dividedBy(3, RoundingMode::Up); // 334

If you're into quotients and remainders, there are methods for this, too:

echo BigInteger::of(1000)->quotient(3); // 333
echo BigInteger::of(1000)->remainder(3); // 1

You can even get both at the same time:

[$quotient, $remainder] = BigInteger::of(1000)->quotientAndRemainder(3);

BigDecimal

Dividing a BigDecimal always requires a scale to be specified. If the exact result of the division does not fit in the given scale, a rounding mode must be provided.

echo BigDecimal::of(1)->dividedBy('8', 3); // 0.125
echo BigDecimal::of(1)->dividedBy('8', 2); // RoundingNecessaryException
echo BigDecimal::of(1)->dividedBy('8', 2, RoundingMode::HalfDown); // 0.12
echo BigDecimal::of(1)->dividedBy('8', 2, RoundingMode::HalfUp); // 0.13

If you know that the division yields a finite number of decimals places, you can use dividedByExact(), which will automatically compute the required scale to fit the result, or throw an exception if the division yields an infinite repeating decimal:

echo BigDecimal::of(1)->dividedByExact(256); // 0.00390625
echo BigDecimal::of(1)->dividedByExact(11); // RoundingNecessaryException

BigRational

The result of the division of a BigRational can always be represented exactly:

echo BigRational::of('13/99')->dividedBy('7'); // 13/693
echo BigRational::of('13/99')->dividedBy('9/8'); // 104/891

Bitwise operations

BigInteger supports bitwise operations:

• and()
• or()
• xor()
• not()

and bit shifting:

• shiftedLeft()
• shiftedRight()

Exceptions

All exceptions thrown by this library implement the MathException interface. This means that you can safely catch all exceptions thrown by this library using a single catch clause:

use Brick\Math\BigDecimal;
use Brick\Math\Exception\MathException;

try {
    $number = BigInteger::of(1)->dividedBy(3);
} catch (MathException $e) {
    // ...
}

If you need more granular control over the exceptions thrown, you can catch the specific exception classes:

• DivisionByZeroException
• IntegerOverflowException
• InvalidArgumentException
• NegativeNumberException
• NoInverseException
• NumberFormatException
• RandomSourceException
• RoundingNecessaryException
• UnsupportedPlatformException

Serialization

BigInteger, BigDecimal and BigRational can be safely serialized on a machine and unserialized on another, even if these machines do not share the same set of PHP extensions.

For example, serializing on a machine with GMP support and unserializing on a machine that does not have this extension installed will still work as expected.

PHPStan extension

A third-party PHPStan extension is available for this library. It provides more specific throw type narrowing for brick/math methods, so that PHPStan can infer the exact exception classes thrown. Note that this extension is not maintained by the author of brick/math.