Tenney norm: Difference between revisions

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{{Wikipedia| James Tenney }}
{{Wikipedia| James Tenney }}


If ''n''/''d'' is a positive rational number reduced to its lowest terms, then the [[Benedetti height]] is the integer ''nd''. Often it is more convenient instead to take the logarithm, usually base 2 ([[log2]]), of the [[Benedetti height]], leading to '''Tenney height'''. In either form it is widely used as a [[measure of inharmonicity]] and/or complexity for intervals. It is also known as ''log product complexity''.
If ''n''/''d'' is a positive rational number reduced to its lowest terms, then the [[Benedetti height]] is the integer ''nd''. Often it is more convenient instead to take the logarithm, usually base 2 ([[log2]]), of the [[Benedetti height]], leading to '''Tenney height'''. In either form it is widely used as a [[measure of inharmonicity]] and/or complexity for intervals.  
 
= Names =
 
In general mathematics, this measurement is known as ''log product complexity''.
 
With respect to microtonal tuning, this measurement was first described by [[James Tenney]], who himself called it ''harmonic distance''<ref>Original paper by Tenney: https://www.plainsound.org/pdfs/JC&ToH.pdf</ref><ref>https://zh.booksc.eu/book/68954431/f87a1d</ref><ref>https://scholar.sun.ac.za/bitstream/handle/10019.1/98644/brand_signal_2016.pdf?sequence=2&isAllowed=y "Tenney's measure of harmonic distance (Hd) is thus singled out as perhaps his most 'crucial development', affording him the means towards 'compactness'. His is a Manhattan, rather than Euclidean metric, defined as Hd (a/b)=k log(ab), with a/ b the maximally
reduced ratio representing the frequency difference, and k=1 indicating measure in octaves."</ref> This terminology was also used in [[Paul Erlich]]'s paper [[A Middle Path]]<ref>Wherein Erlich writes: "This is why, in Tenney’s terminology, the taxicab distance an interval traverses in his lattice is the 'Harmonic Distance' of that interval."</ref>. 
 
= Computation =
 
== Ratio form ==


The Tenney height of a ratio ''n''/''d'' is given by
The Tenney height of a ratio ''n''/''d'' is given by


<math>\log_2 (nd)</math>
<math>\log_2 (nd)</math>
== Vector form ==


The Tenney height of a [[Harmonic limit|''p''-limit]] [[monzo]] b = {{monzo| ''b''<sub>1</sub> ''b''<sub>2</sub> … ''b''<sub>π (''p'')</sub> }} (π being the [[Wikipedia: prime-counting function|prime-counting function]]) is given by
The Tenney height of a [[Harmonic limit|''p''-limit]] [[monzo]] b = {{monzo| ''b''<sub>1</sub> ''b''<sub>2</sub> … ''b''<sub>π (''p'')</sub> }} (π being the [[Wikipedia: prime-counting function|prime-counting function]]) is given by
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<math>W = \operatorname {diag} (1/\log_2 (Q))</math>
<math>W = \operatorname {diag} (1/\log_2 (Q))</math>


== Examples ==
= Examples =
{| class="wikitable"
{| class="wikitable"
! Interval name
! Interval name