Missing Math

This gem includes a variety of methods that I've used occasionally and felt they could be better served as object methods.

Include the gem in an irb/console with

require 'missing_math'

Or in your Gemfile with

gem 'missing-math'

• An is_i? method has been implemented on Fixnum, Float, and Integer classes to return a boolean true|false if the object is an integer. This method is used by the MissingMath module to ensure proper data types before calcuations.
• A similar is_f? method has been implemented with the same concept, and returns boolean true|false if the object is a float.

• to_i has been implemented on the Array class to join an array of numbers and return an integer

• length Returns the character length of the number
  • Example: 12345.length => 5
• to_a Converts a number to an array of integers
  • Example: 12345.to_a => [1, 2, 3, 4, 5]
• prepend(n) Returns the number with a number added to the beginning of the number
  • Example: 2345.prepend(1) => 12345
• append(n) Returns the number with a number added to the end of the number
  • Example: 1234.append(5) => 12345
• shift Returns the number with the first character removed from the beginning of the number
  • Example: 12345.shift => 2345
• pop Returns the number with the last character removed from the end of the number
  • Example: 12345.pop => 1234
• substr(search) Returns a digit subset/substring of the current with a 0-indexed integer or range
  • Example 1: 12345.substr(2) => 3
  • Example 2: 12345.substr(0..2) => 123
• contains?(search) Checks if the number contains a sequence or regex
  • Example 1: 12345.contains?(34) => true
  • Example 2: 12345.contains?(/34/) => true
• rotate(true) Returns the number with the first digit moved to the end
  • Example 1: 12345.rotate => 23451
  • Example 2: 12345.rotate(false) => 51234
• reverse Reverses the number
  • Example: 12345.reverse => 54321
• palindrome? Checks if the number is a palindrome
  • Example: 123454321.palindrome? => true

• prime? Returns boolean true|false if integer is prime
• factorial Returns an integer's factorial n!
• factors(false) Returns an array of an integer's factors
  • Takes one boolean param to include 1 in the output. Default false, set to true to include
• prime_factors Returns an array of the integer's prime factors
• triangle Calculates the triangle number
• pentagon Calculates the pentagonal number
• hexagon Calculates the hexagonal number
• triangular? Checks if the number is triangular. If true, returns the number, otherwise false.
• pentagonal? Checks if the number is pentagonal. If true, returns the number, otherwise false.

• esieve(n, force_new=false) Generates a prime sieve with max value n
  • Calling this method creates a global module variable @esieve. To force it to generate a new @sieve, set force_new to true
  • Example: MissingMath.esieve(1000) => [2, 3, 5, ...]
• fibonacci(n, true_fib=true, force_new=false) Generates an n-length fibonacci sequence
  • Calling this method creates a global module variable @esieve. To force it to generate a new @sieve, set force_new to true
  • This method defaults to using the true fibonacci sequence (0, 1, 1, 2...). To skip the first two values (1, 2, 3, 5...), set true_fib to false
  • Example: MissingMath.fibonacci(5) => [0, 1, 1, 2, 3]

Contributions welcome! This is just something I've been putting together while doing data operations, code challenges, Project Euler problems, etc.

• I'd like to explore different algorithms for efficiency
• Debugging and exception handling
• Features!

In traditional GitHub style:

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request