Factorial primes: Difference between revisions
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(i.28x here would have given us an eleventh prime, but the task asked for the first 10, and the stretch goal requires considerable patience.) |
(i.28x here would have given us an eleventh prime, but the task asked for the first 10, and the stretch goal requires considerable patience.) |
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=={{header|jq}}== |
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The following jq program has been tested with both the C and Go implementations |
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of jq. The latter supports unbounded-precision arithmetic, but the former |
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has sufficient accuracy to compute the first 10 factorial primes. |
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However, the implementation of `is_prime` used here is not sufficiently |
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fast to compute more than the first 10 primes in a reasonable amount of time. |
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<syntaxhighlight lang="jq"> |
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# The algorithm is quite fast because the state of `until` is just a number and we skip by 2 or 4 |
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def is_prime: |
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. as $n |
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| if ($n < 2) then false |
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elif ($n % 2 == 0) then $n == 2 |
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elif ($n % 3 == 0) then $n == 3 |
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else 5 |
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| until( . <= 0; |
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if .*. > $n then -1 |
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elif ($n % . == 0) then 0 |
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else . + 2 |
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| if ($n % . == 0) then 0 |
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else . + 4 |
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end |
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end) |
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| . == -1 |
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end; |
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def factorial_primes: |
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foreach range(1; infinite) as $i (1; . * $i; |
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if ((.-1) | is_prime) then [($i|tostring) + "! - 1 = ", .-1] else empty end, |
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if ((.+1) | is_prime) then [($i|tostring) + "! + 1 = ", .+1] else empty end ) ; |
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limit(20; factorial_primes) |
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| .[1] |= (tostring | (if length > 40 then .[:20] + " .. " + .[-20:] else . end)) |
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| add |
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</syntaxhighlight> |
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Invocation: jq -nr -f factorial-primes.jq |
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{{output}} |
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<pre> |
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1! + 1 = 2 |
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2! + 1 = 3 |
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3! - 1 = 5 |
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3! + 1 = 7 |
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4! - 1 = 23 |
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6! - 1 = 719 |
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7! - 1 = 5039 |
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11! + 1 = 39916801 |
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12! - 1 = 479001599 |
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14! - 1 = 87178291199 |
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# terminated |
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</pre> |
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=={{header|Julia}}== |
=={{header|Julia}}== |
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