# GMP Functions

## Introduction

These functions allow you to work with arbitrary-length integers using the GNU MP library.

These functions have been added in PHP 4.0.4.

> Note: Most GMP functions accept GMP number arguments, defined as resource below. However, most of these functions will also accept numeric and string arguments, given that it is possible to convert the latter to a number. Also, if there is a faster function that can operate on integer arguments, it would be used instead of the slower function when the supplied arguments are integers. This is done transparently, so the bottom line is that you can use integers in every function that expects GMP number. See also the gmp_init() function.

Warning

If you want to explicitly specify a large integer, specify it as a string. If you don't do that, PHP will interpret the integer-literal first, possibly resulting in loss of precision, even before GMP comes into play.

> Note: This extension is available on Windows platforms since PHP 5.1.0.

## Requirements

You can download the GMP library from » http://www.swox.com/gmp/. This site also has the GMP manual available.

You will need GMP version 2 or better to use these functions. Some functions may require more recent version of the GMP library.

## Installation

In order to have these functions available, you must compile PHP with GMP support by using the --with-gmp option.

## Runtime Configuration

This extension has no configuration directives defined in php.ini.

## Resource Types

Most GPM functions operate on or return GMP number resources.

## Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

`GMP_ROUND_ZERO` (integer)
`GMP_ROUND_PLUSINF` (integer)
`GMP_ROUND_MINUSINF` (integer)
`GMP_VERSION` (string)
  The GMP library version

## Examples

Example#1 Factorial function using GMP

`<?php
function fact($x)
{
$return = 1;
for ($i=2; $i < $x; $i++) {
$return = gmp_mul($return, $i);
}
return $return;
}
echo gmp_strval(fact(1000)) . "\n";
?>`

This will calculate factorial of 1000 (pretty big number) very fast.

## See Also

More mathematical functions can be found in the sections BCMath Arbitrary Precision Mathematics Functions and Mathematical Functions.

## Table of Contents

- gmp_abs — Absolute value
- gmp_add — Add numbers
- gmp_and — Logical AND
- gmp_clrbit — Clear bit
- gmp_cmp — Compare numbers
- gmp_com — Calculates one's complement
- gmp_div_q — Divide numbers
- gmp_div_qr — Divide numbers and get quotient and remainder
- gmp_div_r — Remainder of the division of numbers
- gmp_div — Alias of gmp_div_q
- gmp_divexact — Exact division of numbers
- gmp_fact — Factorial
- gmp_gcd — Calculate GCD
- gmp_gcdext — Calculate GCD and multipliers
- gmp_hamdist — Hamming distance
- gmp_init — Create GMP number
- gmp_intval — Convert GMP number to integer
- gmp_invert — Inverse by modulo
- gmp_jacobi — Jacobi symbol
- gmp_legendre — Legendre symbol
- gmp_mod — Modulo operation
- gmp_mul — Multiply numbers
- gmp_neg — Negate number
- gmp_nextprime — Find next prime number
- gmp_or — Logical OR
- gmp_perfect_square — Perfect square check
- gmp_popcount — Population count
- gmp_pow — Raise number into power
- gmp_powm — Raise number into power with modulo
- gmp_prob_prime — Check if number is "probably prime"
- gmp_random — Random number
- gmp_scan0 — Scan for 0
- gmp_scan1 — Scan for 1
- gmp_setbit — Set bit
- gmp_sign — Sign of number
- gmp_sqrt — Calculate square root
- gmp_sqrtrem — Square root with remainder
- gmp_strval — Convert GMP number to string
- gmp_sub — Subtract numbers
- gmp_testbit — Tests if a bit is set
- gmp_xor — Logical XOR