https://github.com/clord/fraction
provides approximate fractions in ruby
https://github.com/clord/fraction
c fraction ruby
Last synced: 6 months ago
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provides approximate fractions in ruby
- Host: GitHub
- URL: https://github.com/clord/fraction
- Owner: clord
- Created: 2010-11-13T19:21:56.000Z (almost 15 years ago)
- Default Branch: master
- Last Pushed: 2019-12-03T21:17:43.000Z (almost 6 years ago)
- Last Synced: 2025-04-10T02:12:45.219Z (6 months ago)
- Topics: c, fraction, ruby
- Language: C
- Homepage: https://rubygems.org/gems/fraction
- Size: 9.77 KB
- Stars: 20
- Watchers: 2
- Forks: 3
- Open Issues: 1
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Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
For a [cooking website][3] I recently worked on,
I needed to display decimal floating point numbers as fractions. I needed to
come up with the fraction closest to what the user typed. For example, 0.33
should resolve to ⅓. When I googled for a solution, most of the code I found
was slow, buggy, and worst of all, too precise (returning 33/100 for the above example.)
I decided to widen my search to C, and [found][1] a piece of code on Stack Overflow
written by David Eppstein in 1993.
It uses the [theory of continued fractions][2] to approach the correct value,
but stops when the denominator reaches some value. The limitation of such an
algorithm is that we can't choose to leave out unnatural denominators
So became `fraction`: it's Eppstein's code in a Ruby gem.
Install it with `gem`:
gem install fraction
Using this gem is easy:
require 'fraction'
num, den = 0.33.to_fraction # num==1, den==3
num, den = 0.33.fraction # legacy name also works
You can get the error:
num,den,err = 0.33.to_fraction #=> [1, 3, -0.0033333333333333]
you can choose a different maximum denominator than the default value of 10:
num, den = 0.51.to_fraction(100) #=> [51, 100, 0.0]
There is also whole fraction support, which factors out any whole numbers:
whole, num, den, error = 3.5.to_whole_fraction #=> [3, 1, 2, 0]
The best part of this gem over others is the speed:
% ruby test.rb
I'm Feeling Lucky: 19.145s
'fraction' gem: 2.090s
subtracting the time required for an empty ruby loop, we can conclude the
algorithm itself requires only ½ of a second for 1,000,000 iterations on my Mac Pro.
[1]: http://stackoverflow.com/questions/95727/how-to-convert-floats-to-human-readable-fractions
[2]: http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/cfINTRO.html#termdecs
[3]: http://freshslowcooking.com
