(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.
exponentmodulusscalescale explicitly specified for calculation results.
If null, the 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)
}