(PHP 8 >= 8.4.0)
BcMath\Number::powmod — Raises an arbitrary precision number, reduced by a specified modulus
$exponent, BcMath\Number|string|int $modulus, ?int $scale = null): BcMath\Number
Use the fast-exponentiation method to raise $this to the power
exponent with respect to the modulus modulus.
exponentmodulusscalenull, the BcMath\Number::scale of the calculation result will be set automatically.
Returns the result as a new BcMath\Number object.
When the BcMath\Number::scale of the result object is automatically set,
the BcMath\Number::scale of the result object will always be 0.
This method throws a ValueError in the following cases:
exponent or modulus is string and not
a well-formed BCMath numeric stringexponent or modulus has a fractional partexponent is a negative valuescale is outside the valid range
This method throws a DivisionByZeroError exception if modulus
is 0.
示例 #1 BcMath\Number::powmod() example when scale is not specified
<?php
var_dump(
new BcMath\Number('8')->powmod(new BcMath\Number('3'), 5),
new BcMath\Number('-8')->powmod(new BcMath\Number('3'), 5),
new BcMath\Number('8')->powmod('2', -3),
new BcMath\Number('-8')->powmod(5, 7),
);
?>以上示例会输出：
object(BcMath\Number)#3 (2) {
["value"]=>
string(1) "2"
["scale"]=>
int(0)
}
object(BcMath\Number)#4 (2) {
["value"]=>
string(2) "-2"
["scale"]=>
int(0)
}
object(BcMath\Number)#2 (2) {
["value"]=>
string(1) "1"
["scale"]=>
int(0)
}
object(BcMath\Number)#5 (2) {
["value"]=>
string(2) "-1"
["scale"]=>
int(0)
}
示例 #2 BcMath\Number::powmod() example of explicitly specifying scale
<?php
var_dump(
new BcMath\Number('8')->powmod(new BcMath\Number('3'), 5, 1),
new BcMath\Number('-8')->powmod(new BcMath\Number('3'), 5, 2),
new BcMath\Number('8')->powmod('2', -3, 3),
new BcMath\Number('-8')->powmod(5, 7, 4),
);
?>以上示例会输出：
object(BcMath\Number)#3 (2) {
["value"]=>
string(3) "2.0"
["scale"]=>
int(1)
}
object(BcMath\Number)#4 (2) {
["value"]=>
string(5) "-2.00"
["scale"]=>
int(2)
}
object(BcMath\Number)#2 (2) {
["value"]=>
string(5) "1.000"
["scale"]=>
int(3)
}
object(BcMath\Number)#5 (2) {
["value"]=>
string(7) "-1.0000"
["scale"]=>
int(4)
}