Diesis (scale theory): Difference between revisions

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-The '''diesis''' (precisely the '''mosdiesis''') of a [[mos scale]] is the interval that is the difference between two enharmonic notes, i.e. the diminished mossecond (a minor mossecond diminished by a [[moschroma]]). In particular, the diesis or '''enharmonic diesis''' in the [[diatonic]] scale is the diminished second, for example, the interval of C#-Db.
+The '''diesis''' (precisely the '''mosdiesis''') of a [[mos scale]] is the interval that is the difference between two enharmonic notes, i.e. the diminished mossecond or the negative diminished mossecond, whichever is positive. In [[soft]] scales, it is the diminished mossecond, since the diminished second itself is negative. In [[hard]] scales, it is the negative diminished second. In particular, the diesis or '''enharmonic diesis''' in the [[diatonic]] scale is the diminished second or the negative diminished second, whichever is positive. For example, the interval of C#-Db or Db-C#.
+If the fifth approximates the just interval [[3/2]], then the diesis or the negative diesis approximates the [[Pythagorean comma]]. In [[meantone]], the diesis also approximates [[128/125]], the augmented comma, which traditionally goes by the name of diesis.
 [[Category:Terms]]
 [[Category:MOS]]