O-I

require 'matrix'

# Input: an array of the n coefficients [a_n, a_n-1,..., a_1] of 
# a univariate polynomial p of degree n ([a_n]x^n + [a_n-1]x^n-1 + ... + a_1)
#
# Output: an array of all n roots of p
#
# Exploits the fact that the eigenvalues of the companion matrix of the
# monic equivalent of p are the roots of p
#

O-I

Further reading on nil in Ruby & Rails

Ruby: Is nil?

• Lukasz Wrobel demystifies nil in Ruby

Why the id of nil is 4 in Ruby

• An older post by Neeraj Singh on nil's object_id

a World Without Nil

O-I

Quicksort

This is an implementation of the quicksort algorithm written in Ruby. Basically, the same code you'll find on Wikibook's entry for quicksort implementations. A gem from the 'Book'.

O-I

def get_character(hexnum)
  char = ''
  char << hexnum.to_i(16)
end