Primality by Wilson's theorem
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- Task
Write a boolean function that tells whether a given integer is prime.
Remember that 1 and all non-positive numbers are not prime.
Use Wilson's theorem.
(% stands for modulo, ! stands for factorial, ² stands for squaring.)
Wilson's theorem states that when the following expression [needs verification] evaluates to the n - 1:
(n-1)!%n
The number is a prime number.
There's also a shorthand for this expression (evaluates into 1 if the number is prime, 0 otherwise):
(n-1)!²%n