4375/4374
| Interval information |
Zoquadyo comma
reduced
4375/4374, the ragisma, is an unnoticeable 7-limit comma with a size of about 0.396 cents. It is the smallest 7-limit superparticular ratio, being the amount by which a stack of two large limmas falls short of 7/6, (7/6)/(27/25)2, as is conveniently codified by its S-expression of S25/S27. It is also the difference between a stack of four classical whole tones (10/9) and 32/21, and the difference between a stack of four classical minor thirds (6/5) octave-reduced and 28/27. In term of other commas, it is equal to the difference between a kleisma and a marvel comma.
Temperaments
Tempering out this comma leads to the ragismic temperament, enabling ragismic chords in the 27-odd-limit. See Ragismic family for the rank-3 family where it is tempered out. See Ragismic microtemperaments for a collection of rank-2 temperaments where it is tempered out.
Etymology
This comma was allegedly named by Erv Wilson no later than 2001[1]. Interestingly, by 2004 people had already lost track of its origin and meaning[2]. It is speculated that it could have been named after Indian ragas.
