Mu badness: Difference between revisions

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{{Texops}}
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'''Mu badness''' is a [[badness]] for [[equal tuning]]s provided by [[User:VectorGraphics|Vector Graphics]], and in a slightly different form by [[User:Lériendil|Lériendil]].  
'''Mu badness''' is a [[badness]] for [[equal tuning]]s provided by {{u|VectorGraphics}}, and in a slightly different form by {{u|Lériendil}}.  


For a given edo ''x'', it is defined as:
For a given EDO ''x'', it is defined as:


$$ \mu \left( x \right) = \sum_{k=1}^{\infty}f \left( x, k \right) $$
$$ \mu \left( x \right) = \sum_{k=1}^{\infty}f \left( x, k \right) $$
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$$ \abs{\operatorname{mod} \left( 2x, 2 \right) - 1} $$
$$ \abs{\operatorname{mod} \left( 2x, 2 \right) - 1} $$


for {{nowrap|''k'' {{=}} 2}}, if integer values of ''x'' are edos.
for {{nowrap|''k'' {{=}} 2}}, if integer values of ''x'' are EDOs.


Equal divisions of any integer ''k'' can be found by multiplying 2''x'' by  
Equal divisions of any integer ''k'' can be found by multiplying 2''x'' by  
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$$ \mu_{s} \left( x \right) = \frac{\left( \frac{\pi^{2}}{6} \right) - \mu \left( x \right)}{\left( \frac{\pi^{2}}{6} \right) - 1} $$
$$ \mu_{s} \left( x \right) = \frac{\left( \frac{\pi^{2}}{6} \right) - \mu \left( x \right)}{\left( \frac{\pi^{2}}{6} \right) - 1} $$


Lériendil prefers to set the denominator to {{frac|π<sup>2</sup>|20}} instead, as it can be shown that this represents a stricter bound on ''μ'' and has the advantage of the maximal possible badness for an [[edo]] being a rational number, 5/9. This also flips the result so that higher values represent worse tunings, as would be expected from a "badness" function.
Lériendil prefers to set the denominator to {{frac|π<sup>2</sup>|20}} instead, as it can be shown that this represents a stricter bound on ''μ'' and has the advantage of the maximal possible badness for an [[EDO]] being a rational number, 5/9. This also flips the result so that higher values represent worse tunings, as would be expected from a "badness" function.


[[File:Mu badness.png|alt=Mu badness.png|1024x107px]]
[[File:Mu badness.png|alt=Mu badness.png|1024x107px]]


Mu badness for equal-step tunings between 1edo and 121edo using {{frac|π<sup>2</sup>|20}} scaling convention. The blue and orange dotted lines represent the best possible odd ed4 and the worst possible edo, respectively.
Mu badness for equal-step tunings between 1EDO and 121EDO using {{frac|π<sup>2</sup>|20}} scaling convention. The blue and orange dotted lines represent the best possible odd ED4 and the worst possible EDO, respectively.


== Peaks and valleys ==
== Peaks and valleys ==
Below is a table of mu badness (''μ''<sub>''s''</sub>(''x'')) for edos, calculated up to {{nowrap|''k'' {{=}} 100}}.
Below is a table of mu badness (''μ''<sub>''s''</sub>(''x'')) for EDOs, calculated up to {{nowrap|''k'' {{=}} 100}}.


{| class="wikitable center-all"
{| class="wikitable center-all"
|-
|-
! Edo
! EDO
! Badness
! Badness
|-
|-
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|}
|}


One can also define mu peaks, similar to zeta peaks. The mu peak integer edos (ignoring zero) calculated up to {{nowrap|''k'' {{=}} 100}} include 1, 2, 3, 5, 12, 41, 53, 441, 494, 612, 2460, 3125, 6079, …. Note that this may differ slightly from the true list, only the first 100 terms of ''μ'' are calculated.
One can also define mu peaks, similar to zeta peaks. The mu peak integer EDOs (ignoring zero) calculated up to {{nowrap|''k'' {{=}} 100}} include 1, 2, 3, 5, 12, 41, 53, 441, 494, 612, 2460, 3125, 6079, …. Note that this may differ slightly from the true list, only the first 100 terms of ''μ'' are calculated.


The mu valley edos calculated up to {{nowrap| ''k'' {{=}} 100 }} include 1, 8, 11, 18, 23, 76, 194, 247, ….  
The mu peaks proper (at the same fidelity) include 1, 2, 3, 5, 12, 41, 53 (52.99916), 171 (170.98894), 441 (441,0088), 494, 612, 2460, 3125...
 
The mu valley EDOs calculated up to {{nowrap| ''k'' {{=}} 100 }} include 1, 8, 11, 18, 23, 76, 194, 247, ….  


The "Parker mu peak integers" are 4, 7, 19, 22, 24, 31, 65, 94, 118, 171, 665, ….  
The "Parker mu peak integers" are 4, 7, 19, 22, 24, 31, 65, 94, 118, 171, 665, ….  
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== Weighted mu ==
== Weighted mu ==
In order to more or less strongly favor lower primes, one can generalize the weighting factor 1/''k''<sup>2</sup> to 1/''k''<sup>''s''</sup>, where ''s'' is a number greater than 1. Note that this requires many more iterations to reasonably converge on a value the closer ''s'' is to 1.
In order to more or less strongly favor lower primes, one can generalize the weighting factor {{frac|1|''k''<sup>2</sup>}} to {{frac|1|''k''<sup>''σ''</sup>}}, where ''σ'' is a number greater than 1. Note that this requires many more iterations to reasonably converge on a value the closer ''σ'' is to 1.
 
== Alternative relative error function ==
If the cosine function is used as the relative error function as opposed to the zigzag, the result is the real part of the [[zeta]] function at {{nowrap|''s'' {{=}} σ + ''ix''}}.


[[Category:Badness]]
[[Category:Badness]]