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In summary, a set of the real numbers is an interval, if and only if it is an open interval, a closed interval, or a half-open interval. [4] [5] A degenerate interval is any set consisting of a single real number (i.e., an interval of the form [a, a]). [6] Some authors include the empty set in this definition.
For example, the interval class between pitch classes 4 and 9 is 5 because 9 − 4 = 5 is less than 4 − 9 = −5 ≡ 7 (mod 12). See modular arithmetic for more on modulo 12. The largest interval class is 6 since any greater interval n may be reduced to 12 − n.
The main objective of interval arithmetic is to provide a simple way of calculating upper and lower bounds of a function's range in one or more variables. These endpoints are not necessarily the true supremum or infimum of a range since the precise calculation of those values can be difficult or impossible; the bounds only need to contain the function's range as a subset.
The harmonic seventh interval, also known as the septimal minor seventh, [2] [3] or subminor seventh, [4] [5] [6] is one with an exact 7:4 ratio [7] (about 969 cents). [8] This is somewhat narrower than and is, "particularly sweet", [ 9 ] "sweeter in quality" than an "ordinary" [ 10 ] just minor seventh , which has an intonation ratio of 9:5 ...
An interval in a poset P is a subset that can be defined with interval notation: For a ≤ b, the closed interval [a, b] is the set of elements x satisfying a ≤ x ≤ b (that is, a ≤ x and x ≤ b). It contains at least the elements a and b.
There is no 'interval class 7' therefore, since counting down five semitones can describe the perfect fifth more parsimoniously that counting up seven semitones can. A visual way to do determine an unordered pitch-class interval is to place the pitch-classes on a clockface and measure clockwise or counter-clockwise, whichever distance is smaller.
Now, 10 years later, we are married. I’m often asked if I knew it would work out; the truth is, I didn’t. It was a risk to ask a stranger to fly to Australia, but with great risk comes great ...
The perfect fourth is a perfect interval like the unison, octave, and perfect fifth, and it is a sensory consonance. In common practice harmony, however, it is considered a stylistic dissonance in certain contexts, namely in two-voice textures and whenever it occurs "above the bass in chords with three or more notes". [ 2 ]