(PHP 5, PHP 7)
bcpowmod — Raise an arbitrary precision number to another, reduced by a specified modulus
$base
, string $exponent
, string $modulus
[, int $scale = 0
] ) : string
Use the fast-exponentiation method to raise
base to the power
exponent with respect to the modulus
modulus.
baseThe base, as an integral string (i.e. the scale has to be zero).
exponentThe exponent, as an non-negative, integral string (i.e. the scale has to be zero).
modulusThe modulus, as an integral string (i.e. the scale has to be zero).
scaleAcest parametru opțional este utilizat pentru a stabili numărul cifrelor după virgulă din rezultat. Dacă este omis, valoarea implicită va fi cea stabilită global cu funcția bcscale(), sau va fi 0 dacă nu a fost stabilită cu ajutorul acestei funcții.
Returns the result as a string, or NULL if modulus
is 0 or exponent is negative.
Notă:
Because this method uses the modulus operation, numbers which are not positive integers may give unexpected results.
The following two statements are functionally identical. The bcpowmod() version however, executes in less time and can accept larger parameters.
<?php
$a = bcpowmod($x, $y, $mod);
$b = bcmod(bcpow($x, $y), $mod);
// $a and $b are equal to each other.
?>