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{{Wikipedia|Septimal kleisma}} | {{Wikipedia|Septimal kleisma}} | ||
The interval of '''225/224''', the '''marvel comma''', otherwise known as the '''septimal kleisma''', is a [[7-limit]] [[superparticular]] [[comma]]. It pops up as the difference between pairs of 7-limit ratios, for example as ([[15/14]])/([[16/15]]) or ([[45/32]])/([[7/5]]). Maybe most simply, it can be seen as the amount by which {{nowrap| [[15/8]] * [[15/8]] exceeds [[7/2]] }}, or equivalently, the amount by which {{nowrap| (15/8)/(16/15) = [[225/128]] }} exceeds 7/4. | The interval of '''225/224''', the '''marvel comma''', otherwise known as the '''septimal kleisma''', is a [[7-limit]] [[superparticular]] [[comma]]. It pops up as the difference between pairs of 7-limit ratios, for example as {{nowrap| ([[15/14]])/([[16/15]]) }} or {{nowrap| ([[45/32]])/([[7/5]]) }}. Maybe most simply, it can be seen as the amount by which {{nowrap| [[15/8]] * [[15/8]] exceeds [[7/2]] }}, or equivalently, the amount by which {{nowrap| (15/8)/(16/15) = [[225/128]] }} exceeds 7/4. | ||
Another useful relation is as the difference between the [[25/24]], the classical chromatic semitone, and [[28/27]], the septimal third-tone. Hence, it is also the difference between [[32/25]] and [[9/7]], and between [[75/64]] and [[7/6]]. | Another useful relation is as the difference between the [[25/24]], the classical chromatic semitone, and [[28/27]], the septimal third-tone. Hence, it is also the difference between [[32/25]] and [[9/7]], and between [[75/64]] and [[7/6]]. |