(PHP 5, PHP 7, PHP 8)
bcpowmod — Raise an arbitrary precision number to another, reduced by a specified modulus
Use the fast-exponentiation method to raise
num to the power
exponent with respect to the modulus
The base, as an integral string (i.e. the scale has to be zero).
The exponent, as an non-negative, integral string (i.e. the scale has to be zero).
The modulus, as an integral string (i.e. the scale has to be zero).
This optional parameter is used to set the number
of digits after the decimal place in the result. If omitted, it will default to the scale set
globally with the bcscale() function, or fallback to
this has not been set.
Returns the result as a string, or
exponent is negative.
The following two statements are functionally identical. The bcpowmod() version however, executes in less time and can accept larger parameters.
$a = bcpowmod($x, $y, $mod);
$b = bcmod(bcpow($x, $y), $mod);
// $a and $b are equal to each other.
Because this method uses the modulus operation, numbers which are not positive integers may give unexpected results.