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>>>>> On Thu, 17 Jun 2021, Guilherme Amadio wrote: |
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> There's actually a much simpler solution to this: |
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> $ is_prime() { test $(factor $1 | cut -d: -f2 | wc -w) == 1; } |
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> $ for n in $(seq 0 10); do is_prime $n && echo $n is prime; done |
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> 2 is prime |
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> 3 is prime |
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> 5 is prime |
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> 7 is prime |
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> $ time factor 20187319083467888113 |
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> 20187319083467888113: 20187319083467888113 |
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> 0.00 |
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This depends on the actual domain of numbers. If the primes involved |
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have 20 digits as in your example, then factor should be used of course. |
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I suspect though that we're talking about small numbers (below 100?) |
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here, in which case a solution in pure bash would be preferable. |
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Ulrich |
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