pub fn roman_numeral_from_chord(
chord: &Chord,
key: Option<&Key>,
) -> Result<Option<RomanNumeral>>Expand description
music21’s romanNumeralFromChord: the numeral a chord is in a key,
written the way music21 writes it. With no key the chord’s root is the
key, major where the chord has a major third and minor otherwise. The
figure is read off the chord’s pitches above its bass, so a chord written
without octaves sounds in octave 4 and G B D F in C major is V43.
An empty chord is no numeral at all.
RomanNumeral::analyze is the crate’s own reading, which names the
chord’s quality rather than every altered degree; this one says what
music21 says, io5b3 and all.