Primality by trial division: Difference between revisions
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{{task|Prime Numbers}}Write a boolean function that tells whether a given integer is prime. Remember that 1 and all non-positive numbers are not prime. |
{{task|Prime Numbers}}Write a boolean function that tells whether a given integer is prime. Remember that 1 and all non-positive numbers are not prime. |
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Use trial division. Even numbers over two may be eliminated right away. |
Use trial division. Even numbers over two may be eliminated right away. |
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A loop from <span style="font-family:serif">3</span> to <span style="font-family:serif">√n</span> will suffice, but other loops are allowed. |
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* Related tasks: [[Sequence of primes by Trial Division]], [[Sieve of Eratosthenes]], [[Prime decomposition]], [[AKS test for primes]]. |
* Related tasks: [[Sequence of primes by Trial Division]], [[Sieve of Eratosthenes]], [[Prime decomposition]], [[AKS test for primes]]. |
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NEXT |
NEXT |
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= TRUE</lang> |
= TRUE</lang> |
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{{out}} |
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'''Output:''' |
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<pre> |
<pre> |
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2 is prime |
2 is prime |
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PAUSE |
PAUSE |
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</lang> |
</lang> |
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{{out}} |
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Output |
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<pre>2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 |
<pre>2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 |
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Press any key to continue...</pre> |
Press any key to continue...</pre> |
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/*Note: // is modulus. */ |
/*Note: // is modulus. */ |
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return 1 /*done dividing, it's prime.*/</lang> |
return 1 /*done dividing, it's prime.*/</lang> |
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{{out}} when using the default input of 10000 |
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<pre style="height:20ex"> |
<pre style="height:20ex"> |
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2 is prime. |
2 is prime. |
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until Num = 0</lang> |
until Num = 0</lang> |
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{{out}} |
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Example output: |
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<pre> |
<pre> |
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777777777 |
777777777 |
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