Direct approximation: Difference between revisions

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"direct mapping" and "patent interval" → "direct approximation", per discussion (and page move)
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A '''direct approximation''' of an interval in a given [[EDO]] is the number of EDO steps that most closely approximates it, found by [[rounding]] to the nearest integer the EDO number times the [[Wikipedia: binary logarithm|binary logarithm]] of the interval: <math>⌈n_{\text{edo}\log_2(i)</math>.
A '''direct approximation''' of an interval in a given [[edo]] is the number of edosteps that most closely approximates it, found by [[rounding]] to the nearest integer the edo number times the [[log2|binary logarithm]] of the interval:  
 
<math>\operatorname {round} (n\log_2(i))</math>
 
for ratio ''i'' in ''n''-edo.  


== Examples of direct approximations ==
== Examples of direct approximations ==
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! [[12edo]] || [[17edo]] || [[19edo]] || [[26edo]]
! [[12edo]] || [[17edo]] || [[19edo]] || [[26edo]]
|-
|-
! Just perfect fifth, [[3/2]]
! Perfect fifth, [[3/2]]
|  7  ||  10  ||  11  || 15
|  7  ||  10  ||  11  || 15
|-
|-
! Just classic major third, [[5/4]]
! Just major third, [[5/4]]
|  4  ||  5  ||  6  || 8
|  4  ||  5  ||  6  || 8
|-
|-
! Just classic minor third, [[6/5]]
! Just minor third, [[6/5]]
|  3  ||  4  ||  5  || 7
|  3  ||  4  ||  5  || 7
|-
|-
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|}
|}


Of these intervals, the fifth plays an important role for characterizing [[EDO]] systems (as it defines the size of M2, m2, A1). Also, a simple test can show if [[circle-of-fifths notation]] can be applied to a given EDO system, because for this the sizes of fifth and octave must be relatively prime.
Of these intervals, the fifth plays an important role for characterizing [[edo]] systems (as it defines the size of M2, m2, A1). Also, a simple test can show if [[circle-of-fifths notation]] can be applied to a given edo system, because for this the sizes of fifth and octave must be relatively prime.


[[Category:Terms]]
[[Category:Terms]]
[[Category:Method]]
[[Category:Method]]
[[Category:Val]]
[[Category:Todo]]