module Prime

Overview

The set of all prime numbers.

== Example

Prime.each(100) do |prime| p prime #=> 2, 3, 5, 7, 11, ...., 97 end

Prime is Enumerable:

Prime.first 5 # => [2, 3, 5, 7, 11]

== Retrieving the instance

For convenience, each instance method of +Prime+.instance can be accessed as a class method of +Prime+.

e.g. Prime.instance.prime?(2) #=> true Prime.prime?(2) #=> true

== Generators

A "generator" provides an implementation of enumerating pseudo-prime numbers and it remembers the position of enumeration and upper bound. Furthermore, it is an external iterator of prime enumeration which is compatible with an Enumerator.

+Prime+::+PseudoPrimeGenerator+ is the base class for generators. There are few implementations of generator.

[+Prime+::+EratosthenesGenerator+] Uses eratosthenes' sieve. [+Prime+::+TrialDivisionGenerator+] Uses the trial division method. [+Prime+::+Generator23+] Generates all positive integers which are not divisible by either 2 or 3. This sequence is very bad as a pseudo-prime sequence. But this is faster and uses much less memory than the other generators. So, it is suitable for factorizing an integer which is not large but has many prime factors. e.g. for Prime#prime? .

Defined in:

prime.cr

Constant Summary

VERSION = "0.1.0"

Class Method Summary

• .each
• .each(upper_bound = nil, generator = Generator::Eratosthenes.new, &)
• .prime?(value, generator = Generator::TwentyThree.new)

Instance Method Summary

• #int_from_prime_division(pd)
• #prime_division(value, generator = Generator::TwentyThree.new)

Class Method Detail

Instance Method Detail