Class: Integer

Inherits:
Object
  • Object
show all
Defined in:
lib/magician/integer.rb

Overview

Magician’s extensions to the Integer class.

Instance Method Summary collapse

Instance Method Details

#factorial ⇒ Integer

Gets the factorial of the integer, which is equivalent to the product of all integers from 1 to the integer (inclusive). When the integer is 0, it is equivalent to 1.

Returns:

  • (Integer) —

    factorial of the integer



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# File 'lib/magician/integer.rb', line 36

def factorial
	return 1 if self == 0
	(1..self).inject(:*)
end

#factors ⇒ Array

Gets all of the factors of the current integer. If the current integer is negative, it will be treated as if it were positive (so the results will never contain negative integers). Returns nil if the integer is 0.

order, including 1 and the integer itself)

Returns:

  • (Array) —

    an array of all of the factors of the current integer (in



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# File 'lib/magician/integer.rb', line 10

def factors
	return nil if self == 0
	return [1] if abs == 1
	#first half
	factors = []
	for i in 1..abs
		if abs % i == 0
			if i < abs/i
				factors << i
			else break
			end
		end
	end
	#second half
	factors_old = factors.dup
	until factors_old.length == 0
		factors << abs/factors_old.pop
	end
	factors
end

#prime? ⇒ Boolean

Returns true if the integer is prime (that is, if it is not divisible by any integer between 1 and the integer itself, exclusive). 0 and 1 are not prime numbers, though 2 is prime. Negative numbers are never considered prime in this implementation.

Returns:

  • (Boolean) —

    true if the integer is prime



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# File 'lib/magician/integer.rb', line 47

def prime?
	return false if self <= 1
	for i in 2..Math.sqrt(self)
		return false if self % i == 0
	end
	true
end