Sinarabian comma: Difference between revisions

One of the major commatic relations is between the rastma (243/242) on one hand, which occurs in the tuning of the mode of Zalzal by [[Wikipedia: al-Farabi|al-Farabi]] (c. 870-950) as the distinction between his steps of [[12/11]] (150.637c) and the smaller 88/81 (143.498c), and, on the other hand, the major minthma (352/351, 4.925c) described by [[Wikipedia: Avicenna|Ibn Sina]] (c.980-1037) in noting the "resemblance" between certain complex superpartient ratios and nearby simpler superparticular ratios, e.g. 128/117 (155.562c) and the simpler 12/11, or 88/81 and the simpler 13/12 (138.573c).  These comparisons relate to the adjacent intervals included in the tetrachrds al-Farabi and Ibn Sina favor to realize the 'oudist Mansur Zalzal's tuning favoring a middle third:

               1/1--------9/8-------27/22-------4/3

In effect, the Sinarabian comma serves as a kind of bridge between these two tetrachords and tunings, hence its name.  More details to come.