Primality by Wilson's theorem: Difference between revisions
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Remember that '''1''' and all non-positive numbers are not prime. |
Remember that '''1''' and all non-positive numbers are not prime. |
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Use Wilson's theorem. |
Use [http://www.cut-the-knot.org/blue/Wilson.shtml Wilson's theorem.] |
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(% stands for modulo, ! stands for factorial, ² stands for squaring.) |
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Wilson's theorem states that when the following expression [needs verification] evaluates to the n - 1: |
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<pre> |
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(n-1)!%n |
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</pre> |
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The number is a prime number. |
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There's also a shorthand for this expression (evaluates into 1 if the number is prime, 0 otherwise): |
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<pre> |
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(n-1)!²%n |
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</pre> |
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Revision as of 04:39, 1 January 2020
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Write a boolean function that tells whether a given integer is prime.
Remember that 1 and all non-positive numbers are not prime.