PHP Manual - collected by Jimbob 2006.03
bcpowmod
(PHP 5)
bcpowmod --
Raise an arbitrary precision number to another, reduced by a specified modulus
Description
string
bcpowmod ( string x, string y, string modulus [, int scale] )
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.
Note:
Because this method uses the modulus operation, non-natural numbers
may give unexpected results. A natural number is any positive
non-zero integer.
Examples
The following two statements are functionally identical. The
bcpowmod() version however, executes in
less time and can accept larger parameters.