Fractional sharp notation: Difference between revisions

VERY WIP (I'll move it to the main namespace if it's finished.)

The '''fractional sharp notation''' (FSN) is a notation developed by [[User:CompactStar|CompactStar]] that is an extension of [[chain-of-fifths notation]], supporting a wide range of [[EDO]] and [[rank-2 temperament]] systems. It represents all intervals with conventional accidentals, but with sharps and flats extended to have an arbitrary rational amount, denoted by a superscript, such as #^1/2 for half-sharp, except for in the case of single and double accidentals. If ASCII compatibility is required, superscripts can be substituted for carets–in this case, #^(a/b) is preferred over #^a/b for clarity.

 

As in the original chain-of-fifths notation, the sharp and flat accidentals are always taken to raise and lower by an augmented union or chromatic semitone. For interval naming, augmented and diminished are expanded to fractional values: a/b-augmented (abbreviated as a/b-A, as in [[User:M-yac/Neutral_Intervals_and_the_FJS#Generalizing|semi-neutral FJS]]) is a/b of a chromatic semitone above a major or perfect interval, and a/b-diminished (abbreviated as a/b-d) is a/b of a chromatic semitone below a minor or perfect interval. Additionally, for intervals between minor and major, a/b-augmented minor is used for a/b chromatic semitones above a minor interval, and a/b-diminished major is used for a/b chromatic semitones below a major interval (this was suggested by [[User:Frostburn|Frostburn]]). 1/2-augmented minor and 1/2-diminished major are identical, corresponding to halfway between minor and major, so both are replaced with the more conventional term "neutral" (abbreviated as lowercase n).

By using a tempered fifth, almost all EDO tunings are supported, since there is support for not only half-sharps and half-flats, but third-sharps, third-flats and so on. Excluding [[1edo]]-[[4edo]] and [[8edo]], there are four EDOs (all multiples of [[7edo]]) that cannot be notated using the native fifth: [[14edo]], [[21edo]], [[28edo]] and [[35edo]]. 36However, it is still possible to notate them with [[subset notation]], using [[42edo]]'s notation for 14edo and 21edo, [[56edo]]'s notation for 28edo, and [[70edo]]'s notation for 35edo. 35edo can additionally be notated using the b val sharp fifth from [[5edo]]. [[2L 5s|Antidiatonic]] fifths may be notated using both the "major wider than minor" and "major narrower than minor" systems, with the former involving swapping sharps/flats, major/minor and augmented/diminished with each other. Accidentals do not stack for large EDOs because of the superscript notation, but the amount of sharps can often be a complicated rational number.

Some [[rank-2 temperament]]s can be notated, but only ones in which the [[period]] and [[generator]] can be expressed as an FSN interval category.  For example, [[neutral]] temperament can have the generator notated as n3, and [[porcupine]] temperament can have the generator notated as 1/3-dM2, because the difference between the generator and [[9/8]] (represented by [[81/80]], [[45/44]] and etc.) is equated to 1/3 of an [[2187/2048|apotome]] in porcupine. [[Semaphore]] is an example of a temperament which does not qualify, because there is no FSN category that implies a semifourth. [[Fractional-octave temperament]]s are not supported, except (peculiarly) 7th-octave temperaments such as [[whitewood]], since 1 step of [[7edo]] is precisely [[9/8]] lowered by 2/7 of an apotome, allowing it to be notated as a 2/7-dM2.