(PHP 5 CVS only)
Use the fast-exponentiation method to raise
x
to the power
y
with respect to the modulus
modulus
. The optional
scale
can be used to set the number of digits after the decimal place
in the result.
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. */ ? |
注意 Because this method uses the modulus operation, non-natural numbers may give unexpected results. A natural number is any positive non-zero integer.