Sha256: 514bbf69231c766491f3324ab6daee6bd8185447353782d562eeabce5b875393
Contents?: true
Size: 897 Bytes
Versions: 11
Compression:
Stored size: 897 Bytes
Contents
module RubyLabs
=begin rdoc
== Sieve of Eratosthenes
The SieveLab module contains the Ruby code described in Chapter 3
of <em>Explorations in Computing</em>.
The module has only one method, +sieve+, which uses the Sieve of Eratosthenes
to generate a list of prime number up to a specified maximum value.
The method is an introduction to iteration, using iterators
to make and filter lists of numbers.
=end
module SieveLab
# Create a list of all prime numbers between 2 and +n+.
#
# Example:
# >> sieve(1000)
# => [2, 3, 5, 7, ... 983, 991, 997]
#
# :call-seq:
# sieve(n) => Array
#
#--
# :begin :sieve
def sieve(n)
worksheet = Array(2..n)
primes = []
while worksheet.first < sqrt(n)
primes << worksheet.first
worksheet.delete_if { |x| x % primes.last == 0 }
end
return primes + worksheet
end
# :end :sieve
end # SieveLab
end # RubyLabs
Version data entries
11 entries across 11 versions & 1 rubygems