Primality testing for the worst case. Panics at zero, flags 1 as prime, 2 as composite. Reduced memory variants
infinitely loop if the input is one of the perfect squares 1194649 or 12327121.This option is intended for proving
primality for integers that have already been checked using simpler methods.
For example one could generate random integers without small factors and then prove that they are prime faster than with
is_prime. Other applications include checking primality within a factorization function.
Approximately 13% faster against primes than is_prime.