Fibonaccia

As though there weren't enough Ruby gems for dealing with the Fibonacci sequence.. here's another one!

Fibonaccia is a very simple package for accessing the series of Fibonacci numbers.

Fibonaccia also provides the irrational constant PHI (φ), which represents the Golden Ratio bu which isn't in Ruby's own Math module.

You can request a specific term in the Fibonacci series:

thirty_fifth = Fibonaccia

or a slice:

fourth_through_seventh = Fibonaccia[4, 3]
fourth_through_seventh = Fibonaccia.slice(4, 3)

or the complete series as far as the module has been requested to derive it:

series_so_far = Fibonaccia.series

or the number of terms in the series-so-far:

term_count = Fibonaccia.terms

or check to see if an arbitrary integer is a Fibonacci number:

Fibonaccia.is_fibonacci?(354224848179261915075)
=> true
Fibonaccia.is_fibonacci?(354224848179261915075 + 1)
=> false

Fibonaccia attempts to be memory-efficient by only deriving the series to the extent needed by the caller (i.e., if you ask for the tenth Fibonacci number, Fibonaccia will internally extend its series to eleven terms if it hasn't already; if you then ask for the eighth number, it will return the value from the already-extended internal series).

Fibonaccia.series
=> [ 0, 1, 1 ]
Fibonaccia.terms
=> 3
Fibonaccia
=> 144
Fibonaccia.series
=> [ 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 ]
Fibonaccia.terms
=> 13
Fibonaccia
=> 21
Fibonaccia.series
=> [ 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 ]
Fibonaccia.terms
=> 13

If memory becomes a concern, you can trim the internal series back to the initial three terms:

Fibonaccia.reset
Fibonaccia.terms
=> 3

You can grow or shrink the list by any number of terms (although you cannot shrink it to fewer than 3):

Fibonaccia.terms
=> 3
Fibonaccia.grow(20)
=> 23
Fibonaccia.terms
=> 23
Fibonaccia.shrink(10)
=> 13
Fibonaccia.terms
=> 13

or you can set the size of the series to any arbitrary number of terms (again, you cannot set the series to fewer than 3 terms):

Fibonaccia.reset
Fibonaccia.terms
=> 3
Fibonaccia.terms = 2048
Fibonaccia.terms
=> 2048

Plans for the Future

I intend to extend this module in the near future to allow requesting arrays of coördinates along a golden spiral, either polar or rectangular.

And who knows what other features may occur.

Installation

Add this line to your application's Gemfile:

gem('fibonaccia')

And then execute:

\$ bundle

Or install it yourself as:

\$ gem install fibonaccia

Usage

require('fibonaccia')

TODO

1. Provide interface for obtaining coördinates on a golden spiral.

Contributing

1. Fork it ( https://github.com/RoUS/fibonaccia/fork )
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 a new Pull Request

Licence

Fibonaccia is copyright © 2015 by Ken Coar, and is made available under the terms of the Apache Licence 2.0: