Tenney norm: Difference between revisions

Much needed readability improvement
Respell ratio as n/d and explicitly give the formula for ratios
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If p/q is a positive rational number reduced to its lowest terms, then the [[Benedetti height]] is the integer pq. 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. It is also known as ''log product complexity''.


The '''Tenney height''' of a [[monzo]] b = {{monzo| ''b''<sub>π (2)</sub> ''b''<sub>π (3)</sub> … ''b''<sub>π (''p'')</sub> }} is given by
The Tenney height of a ratio ''n''/''d'' is given by


<math>\lVert W^{-1}b \rVert = \vert b_{\pi (2)} \vert + \log_2 (3) \vert b_{\pi (3)} \vert + \ldots + \log_2 (p) \vert b_{\pi (p)} \vert = \log_2 (2^{|b_{\pi (2)}|} \cdot 3^{|b_{\pi (2)}|} \cdot \ldots \cdot p^{|b_{\pi (p)}|})</math>
<math>\log_2 (nd)</math>
 
The Tenney height of a [[monzo]] b = {{monzo| ''b''<sub>π (2)</sub> ''b''<sub>π (3)</sub> … ''b''<sub>π (''p'')</sub> }} is given by
 
<math>\lVert W^{-1}b \rVert_1 \\
= \vert b_{\pi (2)} \vert + \log_2 (3) \vert b_{\pi (3)} \vert + \ldots + \log_2 (p) \vert b_{\pi (p)} \vert \\
= \log_2 (2^{|b_{\pi (2)}|} \cdot 3^{|b_{\pi (2)}|} \cdot \ldots \cdot p^{|b_{\pi (p)}|})</math>


where W is the Tenney weighter such that, for the prime basis Q = {{val| 2 3 5 … ''p'' }},  
where W is the Tenney weighter such that, for the prime basis Q = {{val| 2 3 5 … ''p'' }},  
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== Examples ==
== Examples ==
{| class="wikitable"
{| class="wikitable"
! Interval name
! Interval name
! Ratio (p/q)
! Ratio (''n''/''d'')
! Monzo
! Monzo
! Tenney height
! Tenney height
! log2(p*q)
|-
|-
| unison
| Unison
| [[1/1]]
| [[1/1]]
| {{Monzo| 0 }}
| {{Monzo| 0 }}
| 0
| 0
| log2(1)
|-
|-
| octave
| Octave
| [[2/1]]
| [[2/1]]
| {{Monzo| 1 }}
| {{Monzo| 1 }}
| 1
| 1
| log2(1)
|-
|-
| just perfect fifth
| Just perfect fifth
| [[3/2]]
| [[3/2]]
| {{Monzo| -1 1 }}
| {{Monzo| -1 1 }}
| 2.585
| 2.585
| log2(6)
|-
|-
| just major third
| Just major third
| [[5/4]]
| [[5/4]]
| {{Monzo| -2 0 1 }}
| {{Monzo| -2 0 1 }}
| 4.322
| 4.322
| log2(20)
|-
|-
| harmonic seventh
| Harmonic seventh
| [[7/4]]
| [[7/4]]
| {{Monzo| -2 0 0 1 }}
| {{Monzo| -2 0 0 1 }}
| 4.807
| 4.807
| log2(28)
|}
|}