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XXV. GMP functions

These functions allow you to work with arbitrary-length integers using the GNU MP library. In order to have these functions available, you must compile PHP with GMP support by using the --with-gmp option.

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.

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.

Example 1. Factorial function using GMP

<?php
function fact ($x) {
    if ($x <= 1) 
        return 1;
    else
        return gmp_mul ($x, fact ($x-1));
}

print gmp_strval (fact (1000)) . "\n";
?>

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

Table of Contents
gmp_init — Create GMP number
gmp_intval — Convert GMP number to integer
gmp_strval — Convert GMP number to string
gmp_add — Add numbers
gmp_sub — Subtract numbers
gmp_mul — Multiply numbers
gmp_div_q — Divide numbers
gmp_div_r