Supermemo2 (SM2)

A spaced repetition algorithm calculator for Ruby.

Notes

This class is used to calculate easiness factor and interval for study.

Check out the details of how this algorithm is used here: http://www.supermemo.com/english/ol/sm2.htm

Install

Add to your Gemfile:

gem 'spaced_repetition', :git => 'git://github.com/espresse/spaced_repetition.git'

and run

bundle install

Typical use-case:

require 'rubygems'
require 'spaced_repetition'

#user's quality_response is 5; no other arguments are given, because there have been no previous repetitions.
sm2 = SpacedRepetition::Sm2.new(5) 

#user's quality response is 3, his/her prevoius interval was 3 days and easiness factor was 2.1
sm2 = SpacedRepetition::Sm2.new(3,3,2.1)

Now, you can fetch results:

#new interval
new_interval = sm2.interval

#new easiness_factor
new_ef = sm2.easniness_factor

#new repetition date
new_date = sm2.next_repetition_date

If you're a bit confused, check out the test cases for some examples of this class in action.

By default, SM2, uses 6 possible answers (0-5), where 0 is very bad and 5 is perfect.

SM2_mod

If you want to use 4 answers (0 /very bad/ - 3 /perfect/) you can choose SM2Mod. It works in the same manner as SM2 does.

sm2_lg

• TODO: docs?