(PHP 5, PHP 7)
bcpowmod — Raise an arbitrary precision number to another, reduced by a specified modulus
$num
, string $exponent
, string $modulus
, int|null $scale
= null
) : string
Use the fast-exponentiation method to raise
num
to the power
exponent
with respect to the modulus
modulus
.
num
The base, as an integral string (i.e. the scale has to be zero).
exponent
The exponent, as an non-negative, integral string (i.e. the scale has to be zero).
modulus
The modulus, as an integral string (i.e. the scale has to be zero).
scale
Acest 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 false
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.
Versiune | Descriere |
---|---|
8.0.0 |
scale is now nullable.
|
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.
?>