Class TuningSystemAbstract

constructor

• new TuningSystem(name: string, baseFrequency?: number): TuningSystem

  Parameters

  • name: string

    Display name: '12-TET', 'Ptolemaic Just Intonation', 'Werckmeister III'.

  • baseFrequency: number = 440

    Reference frequency for step 0 (A4). Default: 440 Hz.

  Returns TuningSystem

baseFrequency

name

AbstractoctaveSteps

• get octaveSteps(): number

  Number of steps that constitute one period (usually one octave, 2:1). For non-octave tunings (e.g. Bohlen-Pierce) this is steps per tritave.

  Returns number

AbstractgetFrequency

• getFrequency(steps: number): number

  Returns the frequency in Hz for a given step offset from A4.

  Parameters

  • steps: number

  Returns number

AbstractgetInterval

• getInterval(steps: number): Interval

  Returns the Interval from A4 to the given step.

  Parameters

  • steps: number

  Returns Interval

getNoteName

• getNoteName(step: number): string

  Returns a note name for the given step: the 12-TET name of the note the step stands for (getStandardStep), in sharps ("C#4", "A4"), or "Step N" when it stands for none.

  Parameters

  • step: number

  Returns string

getPatternFromStandard

• getPatternFromStandard(pattern: readonly number[]): number[]

  Converts a 12-TET step pattern (successive steps, e.g. major [2, 2, 1, 2, 2, 2, 1]) to this tuning. Each note's position above the first is mapped, not each step, so the pattern keeps its span: in 22-EDO the major scale spans 22 steps (rounding each step would give 24), and in a 7-note JI scale a semitone does not collapse to 0 steps. A step comes out 0 only when two notes land on the same step of this tuning.

  Parameters

  • pattern: readonly number[]

  Returns number[]

getStandardStep

• getStandardStep(step: number): number | null

  The 12-TET note a step stands for: the 12-TET step (A4 = 0) nearest in cents, when getStepFromStandard maps that note back to this step. Names, chord qualities and Roman numerals in any tuning are read through it.

  • In a tuning with 12 steps per octave (12-TET, Werckmeister III, 5-limit JI) every step stands for itself.
  • In 19- or 31-EDO the steps that stand for a note are the meantone images of the 12 notes; in 31-EDO C is step -23 and C# step -21, and steps -22 and -20 stand for none (spelled notes, where the 31-EDO D flat is step -20, are not modelled yet).
  • A quarter tone in 24-EDO stands for none.

  Parameters

  • step: number

  Returns number | null

  The 12-TET step, or null when the step stands for no 12-TET note, and always in a tuning that does not repeat at the octave.

getStepFromStandard

• getStepFromStandard(standardStep: number): number

  Converts a standard 12-TET step (A4 = 0) to the step of this tuning nearest in cents (standardStep × 100¢ above step 0). Works for any tuning whose steps rise: unequal (JI, cent tables, Scala) and non-octave ones alike — in Bohlen-Pierce a fifth (700¢) maps to step 5 (731.6¢). Tunings with 12 steps per octave map one to one.

  Parameters

  • standardStep: number

  Returns number

retuneStep

• retuneStep(step: number, target: TuningSystem): number | null

  The step of target that stands for the same 12-TET note as step does here (getStandardStep on both sides): C4 is step -9 in 12-TET and step -23 in 31-EDO.

  Parameters

  • step: number
  • target: TuningSystem

  Returns number | null

  The step in target, or null when step stands for no note or target has no step for it.