Double Sharp/Flat Notation Check
Parse exact note spelling to normalize x/Unicode accidentals and identify actual double sharp/flat while retaining written octave; does not equate double accidentals with full-step note renaming.
Description
Double accidentals alter a written natural letter by two semitones.
Double accidentals alter a written natural letter by two semitones. Normalizing notation differs from renaming to an enharmonic letter.1
Enter exact uppercase note with optional b/bb/#/##/x or Unicode sharp/flat and optional octave. Normalize x to ## and Unicode marks to ASCII; return name, signed alteration and double flag. Any supplied octave must sound within MIDI 0–127.
When to use Double Sharp/Flat Notation Check
Use Double Sharp/Flat Notation Check when you need to evaluate the supplied records under the calculation and evidence rules below. No key context or enharmonic replacement is applied.
Enter the written notes, explicit grouping, pitch observations or supported chord tokens requested. Keep scientific octaves, accidentals and caller evidence consistent.
How to use Double Sharp/Flat Notation Check 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 noteSpelling using the field table and calculation rules, then run the tool.
- Read normalizedAccidentalSpelling, signedAccidentalSemitones, usesDoubleAccidental. 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 |
|---|---|---|---|
| noteSpelling | Note spelling | string | Required |
Enter exact uppercase note with optional b/bb/#/##/x or Unicode sharp/flat and optional octave. Normalize x to ## and Unicode marks to ASCII; return name, signed alteration and double flag. Any supplied octave must sound within MIDI 0–127.
signedAccidental=#count or−bcount; double=absolute value2 Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| normalizedAccidentalSpelling | Normalized accidental spelling | string |
| signedAccidentalSemitones | Signed accidental semitones | number |
| usesDoubleAccidental | Uses double accidental | boolean |
{
"input": {
"noteSpelling": "Fx4"
},
"output": {
"normalizedAccidentalSpelling": "F##4",
"signedAccidentalSemitones": 2,
"usesDoubleAccidental": true
}
}Limitations and assumptions
No key context or enharmonic replacement is applied.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. 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 Enharmonic Equivalent Lookup: Enharmonic spellings share a sounding MIDI pitch while differing in letter, accidental or written octave. Enumeration needs explicit spelling bounds. For a complementary task, use Note Name to MIDI Converter: Scientific pitch notation combines letter, accidental and octave. Accidentals can cross the written octave boundary while sounding as one MIDI note.
References
-
Double Sharp/Flat Notation Check — tool.io
Similar or alternative tools
- Enharmonic Equivalent Lookup
Enharmonic spellings share a sounding MIDI pitch while differing in letter, accidental or written octave. Enumeration needs explicit spelling bounds.
- Note Name to MIDI Converter
Scientific pitch notation combines letter, accidental and octave. Accidentals can cross the written octave boundary while sounding as one MIDI note.