Chord Inversion From Bass Note

Identify inversion by supplied actual bass in a spelled root/third/fifth/seventh chord, with nonchord bass retained as −1; unlike slash syntax parsing, checks real chord order/quality and octave-independent membership.

Description

Inversion identifies which spelled chord member is the supplied actual bass.

Inversion identifies which spelled chord member is the supplied actual bass. A nonchord bass should remain visible rather than forced into an inversion.^[1]

Enter scientific root, 3–4 scientific chord notes in root/third/fifth/seventh order and actual scientific bass. Require distinct classes, correct tertian letters and recognized triad/seventh set; return index 0–3 or −1, membership and quality.

When to use Chord Inversion From Bass Note

Use Chord Inversion From Bass Note when you need to evaluate the supplied records under the calculation and evidence rules below. Member octaves are ignored and the bass is caller-declared; the tool does not determine the lowest note from audio.

Enter the written notes, explicit grouping, pitch observations or supported chord tokens requested. Keep scientific octaves, accidentals and caller evidence consistent.

How to use Chord Inversion From Bass Note and understand its results

Enter the written notes, explicit grouping, pitch observations or supported chord tokens requested. Keep scientific octaves, accidentals and caller evidence consistent.
Enter rootScientificNote, orderedChordScientificNotes, actualBassScientificNote using the field table and calculation rules, then run the tool.
Read inversionNumber, bassIsChordMember, recognizedTertianChordQuality. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
rootScientificNote	Root scientific note	string	Required
orderedChordScientificNotes	Ordered chord scientific notes	list of string	Required
actualBassScientificNote	Actual bass scientific note	string	Required

inversion=index of bass matching both member pitch class and letter

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
inversionNumber	Inversion number	number
bassIsChordMember	Bass is chord member	boolean
recognizedTertianChordQuality	Recognized tertian chord quality	string

json

{
  "input": {
    "rootScientificNote": "C4",
    "orderedChordScientificNotes": [
      "C4",
      "E4",
      "G4"
    ],
    "actualBassScientificNote": "E3"
  },
  "output": {
    "inversionNumber": 1,
    "bassIsChordMember": true,
    "recognizedTertianChordQuality": "major"
  }
}

Limitations and assumptions

Member octaves are ignored and the bass is caller-declared; the tool does not determine the lowest note from audio.

Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 10,000 entries; string lists to 128 strings of at most 128 characters each. The rules above may impose smaller limits. Extremely large text inputs are rejected. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Slash Chord Bass Validator: A slash symbol specifies a bass pitch independently of the chord’s root. A nonmember pedal bass can be syntactically valid. For a complementary task, use Seventh Chord Type Classifier: Seventh quality depends on the complete root-relative pitch-class set. Doublings do not create additional chord members.

References

Chord Inversion From Bass Note — tool.io

Similar or alternative tools

Slash Chord Bass Validator
A slash symbol specifies a bass pitch independently of the chord’s root. A nonmember pedal bass can be syntactically valid.
Seventh Chord Type Classifier
Seventh quality depends on the complete root-relative pitch-class set. Doublings do not create additional chord members.