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// Implements the Lucas-Lehmer test for Mersenne primes.
// This test is sufficient to prove primality.
//
// To be a Mersenne prime, n must be prime. This function does not first
// test that, as it is assumed that some sort of preliminary sieving has
// occurred.
// NOTE:
// As of the 2005-11-12 release of Frink, the isPrime[x] routine automatically
// detects if a number is of the form 2^n-1 and uses this more efficient
// Lucas-Lehmer test, rather than the usual Rabin-Miller tests.
// Returns true if 2^n - 1 is prime, false otherwise.
isMersennePrime[n] :=
{
m = 2^n-1
s = 4
for i = 2 to n-1
s = (modPow[s,2,m] - 2) mod m // modPow[base,exp,m] is base^exp mod m
// Return true (prime) if s is equal to zero, false otherwise.
return s==0
}
Download or view LucasLehmer.frink in plain text format
This is a program written in the programming language Frink.
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Alan Eliasen was born 19971 days, 21 hours, 45 minutes ago.