27edo: Difference between revisions

! colspan="2" | Standard<br />notation !! colspan="2" | Quarter tone<br />notation

| 0

| 711.11

| 222.22

| 933.33

| 444.44

| 1155.55

| 666.66

| colspan="2" | F&#x266F;

| 177.77

| colspan="2" | C&#x266F;

| 888.88

| colspan="2" | G&#x266F;

| 400

| colspan="2" | D&#x266F;

| 1111.11

| colspan="2" | A&#x266F;

| 622.22

| colspan="2" | E&#x266F;

| 133.33

| B&#x266F;

| F&#x1D12B;

| 844.44

| F&#x1D12A;

| C&#x1D12B;

| 355.56

| C&#x1D12A;

| G&#x1D12B;

| 1066.67

| G&#x1D12A;

| D&#x1D12B;

| 577.78

| D&#x1D12A;

| A&#x1D12B;

| 88.89

| A&#x1D12A;

| E&#x1D12B;

| 800

| E&#x1D12A;

| B&#x1D12B;

| 311.11

| B&#x1D12A;

| F&#x266D;

| 1022.22

| colspan="2" | C&#x266D;

| 533.33

| colspan="2" | G&#x266D;

| 44.44

| colspan="2" | D&#x266D;

| 755.56

| colspan="2" | A&#x266D;

| 266.67

| colspan="2" | E&#x266D;

| 977.78

| colspan="2" | B&#x266D;

| 488.89

| 0

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 [[circle-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&#x266D;, C{{demisharp2}}, D{{demiflat2}}, C&#x266F;, 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&#x266D; 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&#x266D; is not only familiar, though here very exaggerated, to those working with the Pythagorean scale (see [[53edo]]), but also to many classically trained violinists.

{{sharpness-sharp4}}

This notation is a subset of the notation for [[54edo#Sagittal notation|54-EDO]].

In the diagrams above, a sagittal symbol followed by an equals sign (=) means that the following comma is the symbol's [[Sagittal notation#Primary comma|primary comma]] (the comma it ''exactly'' represents in JI), while an approximately equals sign (≈) means it is a secondary comma (a comma it ''approximately'' represents in JI). In both cases the symbol exactly represents the tempered version of the comma in this EDO.

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 &#x266F; and &#x266D;.