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* lib/prime.rb: Simplify and optimize EratosthenesSieve

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50802 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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marcandre 2015-06-09 03:32:11 +00:00
parent d46336e717
commit 9d3c64a40a
1 changed files with 4 additions and 3 deletions
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lib/prime.rb
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@ -424,10 +424,11 @@ class Prime
segment_max = [segment_min + max_segment_size, max_cached_prime * 2].min
root = Integer(Math.sqrt(segment_max).floor)
sieving_primes = @primes[1 .. -1].take_while { |prime| prime <= root }
segment = ((segment_min + 1) .. segment_max).step(2).to_a
sieving_primes.each do |prime|
(1..Float::INFINITY).each do |sieving|
prime = @primes[sieving]
break if prime > root
composite_index = (-(segment_min + 1 + prime) / 2) % prime
while composite_index < segment.size do
segment[composite_index] = nil