EFD: Difference between revisions
Rework (1/2, improve intro, +new terms, and formatting) |
Rework (2/2, efd is no longer reserved for irrational periods) |
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</math> | </math> | ||
This way, when <math>k</math> is <math>0</math>, <math> | This way, when <math>k</math> is <math>0</math>, <math>c</math> is simply <math>1</math>. And when <math>k</math> is <math>n</math>, <math>c</math> is simply <math>1 + (p-1) = p</math>. | ||
== Relationship to other tunings == | == Relationship to other tunings == | ||
=== Vs. EPD === | === Vs. EPD === | ||
Instead of equally dividing the octave into 12 equal parts by pitch, as is done for | Instead of equally dividing the octave into 12 equal parts by pitch, as is done for 12epdo, or 12edo (because pitch can be assumed), standard tuning, you could divide it into 12 equal parts by ''frequency''. This would give you 12efdo. | ||
=== Vs. OD === | |||
OD is equivalent to EFD, except that the period of OD is rational. | |||
=== Vs. ELD === | === Vs. ELD === | ||
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=== Vs. AFS === | === Vs. AFS === | ||
An EFD will be equivalent to some [[AFS|AFS, or arithmetic frequency sequence]], which has had its count of pitches specified by prefixing "n-"; specifically, n- | An EFD will be equivalent to some [[AFS|AFS, or arithmetic frequency sequence]], which has had its count of pitches specified by prefixing "''n''-"; specifically, ''n''-efd-''p'' = ''n''-AFS((''p'' - 1)/''n''). | ||
== Examples == | == Examples == | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+Example: 4efdφ | ||
|- | |- | ||
! | ! Steps | ||
! | ! 0 | ||
! 1 | ! 1 | ||
! 2 | ! 2 | ||
| Line 47: | Line 44: | ||
! 4 | ! 4 | ||
|- | |- | ||
! | ! Frequency Ratios (''r'') | ||
| | | 1 + (0/4)(φ - 1)<br>= (0φ + 4)/4<br>= 1 | ||
|1+(1/4)(φ-1) = (1φ + 3)/4 | | 1 + (1/4)(φ - 1)<br>= (1φ + 3)/4 | ||
|1+(2/4)(φ-1) = (2φ + 2)/4 | | 1 + (2/4)(φ - 1)<br>= (2φ + 2)/4 | ||
|1+(3/4)(φ-1) = (3φ + 1)/4 | | 1 + (3/4)(φ - 1)<br>= (3φ + 1)/4 | ||
|1+(4/4)(φ-1) = (4φ + 0)/4 = φ | | 1 + (4/4)(φ - 1)<br>= (4φ + 0)/4<br>= φ | ||
|- | |- | ||
! | ! Octaves (log<sub>2</sub>''r'') | ||
| | | 0 | ||
|0.21 | | 0.21 | ||
|0.39 | | 0.39 | ||
|0.55 | | 0.55 | ||
|0.69 | | 0.69 | ||
|- | |- | ||
! | ! Length Ratios (1/''r'') | ||
| | | 1 | ||
| | | 4/(φ + 3) | ||
| | | 2/(φ + 1) | ||
| | | 4/(3φ + 1) | ||
|1/φ | | 1/φ | ||
|} | |} | ||