XXXVI. 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.
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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.
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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";
?>
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This will calculate factorial 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 -- Remainder of the division of
numbers
- gmp_div_qr -- Divide numbers and get quotient
and remainder
- gmp_div -- Divide numbers
- gmp_mod -- Modulo operation
- gmp_divexact -- Exact division of
numbers
- gmp_cmp -- Compare numbers
- gmp_neg -- Negate number
- gmp_com -- Calculates one's complement of a
- gmp_abs -- Absolute value
- gmp_sign -- Sign of number
- gmp_fact -- Factorial
- gmp_sqrt -- Square root
- gmp_sqrtrm -- Square root with remainder
- gmp_perfect_square -- Perfect square
check
- gmp_pow -- Raise number into power
- gmp_powm -- Raise number into power with
modulo
- gmp_prob_prime -- Check if number is
"probably prime"
- gmp_gcd -- Calculate GCD
- gmp_gcdext -- Calculate GCD and
multipliers
- gmp_invert -- Inverse by modulo
- gmp_legendre -- Legendre symbol
- gmp_jacobi -- Jacobi symbol
- gmp_random -- Random number
- gmp_and -- Logical AND
- gmp_or -- Logical OR
- gmp_xor -- Logical XOR
- gmp_setbit -- Set bit
- gmp_clrbit -- Clear bit
- gmp_scan0 -- Scan for 0
- gmp_scan1 -- Scan for 1
- gmp_popcount -- Population count
- gmp_hamdist -- Hamming distance
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