Class: Tonal::Scale::Step

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
Comparable
Defined in:
lib/tonal/step.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(modulo: nil, log: nil, step: nil, ratio: nil) ⇒ Step

Returns a new instance of Step.

Raises:

  • (ArgumentError) 


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# File 'lib/tonal/step.rb', line 10

def initialize(modulo: nil, log: nil, step: nil, ratio: nil)
  raise ArgumentError, "modulo: required" unless modulo
  raise ArgumentError, "One of log:, step: or ratio: must be provided" unless [log, step, ratio].compact.count == 1
  @modulo = modulo.round

  if ratio
    @ratio, @log = derive_ratio_and_log(ratio: ratio)
  elsif step
    @ratio, @log = derive_ratio_and_log(step: step)
  elsif log
    @ratio, @log = derive_ratio_and_log(log: log)
  end

  @step = (modulo * @log).round
  @tempered = 2**(@step.to_f/@modulo)
end

Instance Attribute Details

#log ⇒ Object (readonly)

Returns the value of attribute log.



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# File 'lib/tonal/step.rb', line 8

def log
  @log
end

#modulo ⇒ Object (readonly)

Returns the value of attribute modulo.



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# File 'lib/tonal/step.rb', line 8

def modulo
  @modulo
end

#ratio ⇒ Object (readonly)

Returns the value of attribute ratio.



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# File 'lib/tonal/step.rb', line 8

def ratio
  @ratio
end

#step ⇒ Object (readonly)

Returns the value of attribute step.



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# File 'lib/tonal/step.rb', line 8

def step
  @step
end

#tempered ⇒ Object (readonly)

Returns the value of attribute tempered.



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# File 'lib/tonal/step.rb', line 8

def tempered
  @tempered
end

Instance Method Details

#+(rhs) ⇒ Object Also known as: %

Returns a new [Tonal::Scale::Step] with the step added to the current step.

Examples:

Tonal::Scale::Step.new(step: 5, modulo: 12) + Tonal::Scale::Step.new(step: 7, modulo: 12) => 0\12

Returns:

  • a new [Tonal::Scale::Step] with the step added to the current step



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# File 'lib/tonal/step.rb', line 127

def +(rhs)
  self.class.new(step: (rhs % modulo), modulo: modulo)
end

#<=>(rhs) ⇒ Object 



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# File 'lib/tonal/step.rb', line 132

def <=>(rhs)
  rhs.kind_of?(self.class) && modulo <=> rhs.modulo && log <=> rhs.log && step <=> rhs.step
end

#convert(new_modulo) ⇒ Object

Returns a new [Tonal::Scale::Step] with the ratio mapped to the new modulo.

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).convert(12)
=> 7\12

Returns:

  • a new [Tonal::Scale::Step] with the ratio mapped to the new modulo



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# File 'lib/tonal/step.rb', line 37

def convert(new_modulo)
  self.class.new(log: log, modulo: new_modulo)
end

#coprime? ⇒ Boolean

Returns true if the step is coprime to the modulo.

Examples:

Tonal::Scale::Step.new(step: 5, modulo: 12).coprime? => true
Tonal::Scale::Step.new(step: 6, modulo: 12).coprime? => false

Returns:

  • (Boolean) —

    true if the step is coprime to the modulo



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# File 'lib/tonal/step.rb', line 119

def coprime?
  step.coprime?(modulo)
end

#efficiency ⇒ Object Also known as: cents_difference

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).efficiency => 5.19 ยข


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# File 'lib/tonal/step.rb', line 108

def efficiency
  # We want the efficiency from the step (self). The tempered value is the tempered approximation of the ratio, so we want to know how far off the step is from the ratio. So we take the ratio and subtract the tempered value.
  ratio_to_cents - tempered_to_cents
end

#inspect ⇒ Object Also known as: to_s 



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# File 'lib/tonal/step.rb', line 27

def inspect
  "#{step}\\#{modulo}"
end

#ratio_to_cents ⇒ Object

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).ratio_to_cents
=> 701.96


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# File 'lib/tonal/step.rb', line 100

def ratio_to_cents
  ratio.to_cents
end

#ratio_to_r ⇒ Object

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).ratio_to_r
=> (3/2)


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# File 'lib/tonal/step.rb', line 82

def ratio_to_r
  ratio.to_r
end

#step_to_midi(midi_root: Tonal::Midi::Note::C4_MIDI_NUMBER) ⇒ Object

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).step_to_midi
=> 78
Tonal::Scale::Step.new(ratio: 3/2r, modulo: 12).step_to_midi
=> 67
Tonal::Scale::Step.new(ratio: 3/2r, modulo: 12).step_to_midi(midi_root: Tonal::Midi::Note::A4_MIDI_NUMBER)
=> 76

Parameters:

  • midi_root (Integer) (defaults to: Tonal::Midi::Note::C4_MIDI_NUMBER) —

    the MIDI number that corresponds to the 0 step of the scale. Default is C4 (60 MIDI).



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# File 'lib/tonal/step.rb', line 73

def step_to_midi(midi_root: Tonal::Midi::Note::C4_MIDI_NUMBER)
  Tonal::Midi::Note.new(number: step + midi_root)
end

#step_to_r ⇒ Object

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).step_to_r
=> (18/31)
Tonal::Scale::Step.new(ratio: 3/2r, modulo: 34).step_to_r
=> (10/17)


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# File 'lib/tonal/step.rb', line 48

def step_to_r
  Rational(step, modulo)
end

#step_to_ratio ⇒ Object

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).step_to_ratio
=> 18/31


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# File 'lib/tonal/step.rb', line 57

def step_to_ratio
  Tonal::Ratio.new(step, modulo)
end

#tempered_to_cents ⇒ Object

Examples:

Tonal::Scale::Step.new(ratio: 3/2r, modulo: 31).tempered_to_cents
=> 696.77


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# File 'lib/tonal/step.rb', line 91

def tempered_to_cents
  tempered.to_cents
end