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XXXVI. GMP functions
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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.
ע: 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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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.
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In order to have these functions available, you must compile PHP with GMP support by using the --with-gmp option.
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=ד 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 factorial of 1000 (pretty big number) very fast.
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More mathmatical functions can be found in the sections BCMath Arbitrary Precision Mathematics Functions and Mathematical Functions.
Ŀ¼ 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 -- Divide numbers 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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