27edo: Difference between revisions

! rowspan="2" | [[Cent]]s !! colspan="6" | Note from C

! colspan="2" | Standard<br>notation !! colspan="2" | Quartertone<br>notation

| 0.0

| colspan="2" | C

| colspan="2" | A{{sesquisharp2}}

| 711.1

| colspan="2" | G

| colspan="2" | E{{sesquisharp2}}

| 222.2

| colspan="2" | D

| B{{sesquisharp2}} || F{{sesquiflat2}}

| 933.3

| colspan="2" | A

| colspan="2" | C{{sesquiflat2}}

| 444.4

| colspan="2" | E

| colspan="2" | G{{sesquiflat2}}

| 1155.6

| colspan="2" | B

| colspan="2" | D{{sesquiflat2}}

| 666.7

| colspan="2" | F♯

| colspan="2" | A{{sesquiflat2}}

| 177.8

| colspan="2" | C♯

| colspan="2" | E{{sesquiflat2}}

| 888.9

| colspan="2" | G♯

| colspan="2" | B{{sesquiflat2}}

| 400.0

| colspan="2" | D♯

| colspan="2" | F{{demiflat2}}

| 1111.1

| colspan="2" | A♯

| colspan="2" | C{{demiflat2}}

| 622.2

| colspan="2" | E♯

| colspan="2" | G{{demiflat2}}

| 133.3

| B♯

| F𝄫

| colspan="2" | D{{demiflat2}}

| 844.4

| F𝄪

| C𝄫

| colspan="2" | A{{demiflat2}}

| 355.6

| C𝄪

| G𝄫

| colspan="2" | E{{demiflat2}}

| 1066.7

| G𝄪

| D𝄫

| colspan="2" | B{{demiflat2}}

| 577.8

| D𝄪

| A𝄫

| colspan="2" | F{{demisharp2}}

| 88.9

| A𝄪

| E𝄫

| colspan="2" | C{{demisharp2}}

| 800.0

| E𝄪

| B𝄫

| colspan="2" | G{{demisharp2}}

| 311.1

| B𝄪

| F♭

| colspan="2" | D{{demisharp2}}

| 1022.2

| colspan="2" | C♭

| colspan="2" | A{{demisharp2}}

| 533.3

| colspan="2" | G♭

| colspan="2" | E{{demisharp2}}

| 44.4

| colspan="2" | D♭

| colspan="2" | B{{demisharp2}}

| 755.6

| colspan="2" | A♭

| colspan="2" | F{{sesquisharp2}}

| 266.7

| colspan="2" | E♭

| colspan="2" | C{{sesquisharp2}}

| 977.8

| colspan="2" | B♭

| colspan="2" | G{{sesquisharp2}}

| 488.9

| colspan="2" | F

| colspan="2" | D{{sesquisharp2}}

| 0.0

| colspan="2" | C

| colspan="2" | A{{sesquisharp2}}

The 27-note system can be notated using [[ups and downs notation]], in which case arrows or [[Helmholtz-Ellis notation|Helmholtz–Ellis]] accidentals can be used, or with a variation on quarter tone accidentals. With standard [[chain-of-fifths notation]], a sharp raises a note by 4 steps, just one step beneath the following nominal (for example C to C♯ describes the approximate 10/9 and 11/10 interval) and the flat conversely lowers: these are augmented unisons and diminished unisons. Just so, one finds that an accidental can be divided in half, and the remaining places can then be filled in with half-sharps, half-flats, sesquisharps, and sesquiflats, reducing the need for double sharps and double flats.The notes from C to D are C, D♭, C{{demisharp2}}, D{{demiflat2}}, C♯, and D, with some ascending intervals appearing to be descending on the staff.

Another notational implication is that, being a Superpythagorean system, the 5/4 major third present in the 4:5:6 chord is technically an augmented second, since (for example) C–E is a 9/7 supermajor third and so the note located one major third above C must be notated as D♯ or E{{naturaldown}}. Conversely, the 6/5 minor third of a 10:12:15 chord is actually reached by a diminished fourth, since (for example) D–F is a 7/6 subminor third and so the note located one minor third above D must be notated as either G♭ or F{{naturalup}}. The composer can decide for themselves which additional accidental pair is appropriate if they will need redundancy to remedy these problems, and to keep the chromatic pitches within a compass on paper relative to the natural names (C, D, E etc.). Otherwise it is simple enough, and the same tendency for A♯ to be higher than B♭ is not only familiar, though here very exaggerated, to those working with the Pythagorean scale (see [[53edo]]), but also to many classically trained violinists.

The notation of Tetracot[7]. Notes are denoted as {{nowrap|LLLLLLs {{=}} CDEFGABC}}, and raising and lowering by a chroma {{nowrap|(L − s)}}, 1 step in this instance, is denoted by ♯ and ♭.  

| aug 1sn, double-dim 2nd

| double-aug 1sn, dim 2nd

| minor 2nd

| major 2nd

| minor 7th

| major 7th

| aug 7th, double-dim 8ve

| double-aug 7th, dim 8ve