GMP Functions

gmp_abs — Absolute value
gmp_add — Add numbers
gmp_and — Bitwise 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_export — Export to a binary string
gmp_fact — Factorial
gmp_gcd — Calculate GCD
gmp_gcdext — Calculate GCD and multipliers
gmp_hamdist — Hamming distance
gmp_import — Import from a binary string
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 — Bitwise 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_bits — Random number
gmp_random_range — Random number
gmp_random_seed — Sets the RNG seed
gmp_random — Random number
gmp_root — Take the integer part of nth root
gmp_rootrem — Take the integer part and remainder of nth root
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 — Bitwise XOR

User Contributed Notes

5 years ago


I made a function that can be used for converting numbers to any base you wish.. instead of returning a string of pre-defined index of characters (i.e. 0-9a-z) you could simply make your own of any length using the array of indexes it returns.

I looked around and didn't see anybody made one, I needed one for a simple compression algorithm with only numbers, I've not actually made it yet but this was an initial idea.



<?php

// ConvertBase function explained:

// we add an array item $Input%$Base floored and divide $Input by $Base floored.

// repeat until $Input is no longer above 0.



function ConvertBase($Input,$Base=10) {

  $Input=gmp_init($Input);

  $Result=array();



  for($i=0;$i<1||gmp_sign($Input)==1;$i++) {

    $Result[]=gmp_intval(gmp_mod($Input,$Base));

    $Input=gmp_div_q($Input,$Base);

  }

  $Result=array_reverse($Result);

  return($Result);

}



// an example how gmp_strval($.., 36); could be achieved:



// the funny emergency number from The IT Crowd

// (leading zeroes aren't liked in gmp_init though)

$Input = '1189998819991197253';



// our example 36 characters used in gmp_strval($.., 36);

$Chars = '0123456789abcdefghijklmnopqrstuvwxyz';



// count the $Chars so they're all used

// or use your own number less than the length of $Chars

$Base = strlen($Chars);



// perform

$Result = ConvertBase($Input,$Base);



// replace the resulting index with the corrosponding characters of the index in $Chars

for($i=0;$i<count($Result);$i++)

  $Result[$i]=$Chars{$Result[$i]};



// compare

printf("gmp_strval:  %s\r\n",gmp_strval($Input,36));

printf("BaseConvert: %s\r\n",implode($Result));



/* OUTPUT:

gmp_strval:  91h7dixfq6h1

BaseConvert: 91h7dixfq6h1

*/

?>

The example shows a familiar result of course, but the idea of this function was so that you can use whatever base you wish, and display entirely your own output to represent any number of choice.



Also, for those who wish to do bitwise shifting, it's quite simple.. to shift left, just multiply the number by pow(2,x), and to shift right, divide by pow(2,x).



<?php

function gmp_shiftl($x,$n) { // shift left

  return(gmp_mul($x,gmp_pow(2,$n)));

}



function gmp_shiftr($x,$n) { // shift right

  return(gmp_div($x,gmp_pow(2,$n)));

}

?>



Have fun,

Nitrogen.

richard-slater.co.uk

12 years ago


For those (like me) who are trying to do bit masking with very large numbers, here is a useful function to do the work for you.

<?php
  function isBitSet($bitMask, $bitMap)
  {
    return (bool) gmp_intval(gmp_div(gmp_and($bitMask, $bitMap),$bitMask));
  }
?>

john at worldmapad dot com

9 years ago


Here's a quick and dirty way to use simple GMP functions with PHP without recompiling. It is dependent upon the use of the exec() function, so make sure you can use exec(). While in safe mode you must consider the safe_mode_exec_dir directive. And don't simply pass user input to the exec function without validating the input first!

Download and Install GMP as instructed in README and INSTALL files.
On my MAC OS X Server, I just did the following:
./configure
make
make check
make install
This installed it in the /usr/local directory. There were some errors, but not with any functions I needed.
Within the gmp-4.#.# cd into the demos directory. Then compile pexpr.c by typing:
make pexpr
This is a simple expressions parser which serves as a simple interface to some of the basic GMP functions.
You can test it then like:
./pexpr "102394874783 * 23498748";
Now you may interface with it using PHP's exec() function.

GMP Functions

See Also

Table of Contents

User Contributed Notes