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XXXVI. 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 not available on Windows platforms.

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

   This extension has no resource types defined.

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)

Examples

   Example 1. Factorial function using GMP
   <?php
   function fact($x) {
       if ($x <= 1) {
           return 1;
       } else {
           return gmp_mul($x, fact($x-1));
       }
   }
   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 of a
   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_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 -- Square root
   gmp_sqrtrm -- Square root with remainder
   gmp_strval -- Convert GMP number to string
   gmp_sub -- Subtract numbers
   gmp_xor -- Logical XOR
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