Category talk:Wren-math: Difference between revisions
Content added Content deleted
m (→Source code: Minor change.) |
(→Source code: Removed some private methods which are no longer used.) |
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} |
} |
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return allPrimes |
return allPrimes |
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} |
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// Private helper method which counts and returns how many primes there are |
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// up to and including 'n' using the Legendre method. |
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static phi_(n, a, primes) { |
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if (a <= 1) return (a < 1) ? n : n - (n >> 1) |
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var pa = primes[a-1] |
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if (n <= pa) return 1 |
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return phi_(n, a-1, primes) - phi_((n/pa).floor, a-1, primes) |
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} |
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// As above method but uses memoization. |
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static phi_(n, a, primes, cache) { |
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if (a <= 1) return (a < 1) ? n : n - (n >> 1) |
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var pa = primes[a-1] |
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if (n <= pa) return 1 |
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var key = Int.cantorPair(n, a) |
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if (cache.containsKey(key)) return cache[key] |
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return cache[key] = phi_(n, a-1, primes, cache) - phi_((n/pa).floor, a-1, primes, cache) |
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} |
} |
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