music.rb

module Roots
  def self.rootn(x,n)
    Math.exp(Math.log(x)/n)
  end
end

module Notes
  def self.c accidental, octave
    Note.new(4, octave, accidental)
  end

  def self.e accidental, octave
    Note.new(8, octave, accidental)
  end
end

Note = Struct.new(:base_pitch, :octave, :accidental) do
  def pitch
    simple_pitch = base_pitch + (octave-1) * 12
    return simple_pitch + 1 if accidental == :sharp
    return simple_pitch - 1 if accidental == :flat
    simple_pitch
  end

  def frequency
    freq = (Roots.rootn(2, 12) ** (pitch - 49) ) * 440
    freq.round(4)
  end
end


module Interval
  def self.between first, second
    case second.pitch - first.pitch
    when 4
       return :major_third
    when 3
       return :minor_third
    end
  end
end