Sha256: 370e2c6d5d37ccce46f432e3c21e0e0ed4946b944974840d7e59bf9b42fbddee
Contents?: true
Size: 971 Bytes
Versions: 22
Compression:
Stored size: 971 Bytes
Contents
# frozen_string_literal: true
module Coltrane
module Theory
class CircleOfFifths
attr_reader :notes
LETTER_SEQUENCE = %w[C G D A E B F].freeze
def initialize(start_note = Note['C'], size = Float::INFINITY)
index = letters.index(start_note.name[0])
@notes = fifths(note: start_note - Interval.perfect_fifth,
size: size,
index: (index - 1) % LETTER_SEQUENCE.size)
end
private
def fifths(note:, index: nil, notes: [], size:)
return notes if size == 0
return notes if notes.any? && note.as(letters(index)).name == notes.first.name
fifths note: note + Interval.perfect_fifth,
notes: notes + [note.as(letters(index))],
index: index + 1,
size: size - 1
end
def letters(i = nil)
i.nil? ? LETTER_SEQUENCE : LETTER_SEQUENCE[i % LETTER_SEQUENCE.size]
end
end
end
end
Version data entries
22 entries across 22 versions & 1 rubygems