Delta
The delta of a ratio is simply the difference between the numerator and the denominator. Thus superparticular ratios like 9/8 are delta-1 ratios. Ratios of the form [math]\displaystyle{ \frac{n+2}{n} }[/math] like 7/5 are delta-2.
| delta-1 ratios | 2/1 | 3/2 | 4/3 | 5/4 | 6/5 | 7/6 | etc. |
|---|---|---|---|---|---|---|---|
| delta-2 ratios | 3/1 | 5/3 | 7/5 | 9/7 | 11/9 | 13/11 | etc. |
| delta-3 ratios | 4/1 | 5/2 | 7/4 | 8/5 | 10/7 | 11/8 | etc. |
| delta-4 ratios | 5/1 | 7/3 | 9/5 | 11/7 | 13/9 | 15/11 | etc. |
The term delta was coined by Kite Giedraitis.