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Re: Microtonal Helmholtz-Ellis notation in Lilypond: fine-tuning

 From: Hans Aberg Subject: Re: Microtonal Helmholtz-Ellis notation in Lilypond: fine-tuning Date: Sat, 26 Sep 2009 19:35:23 +0200

```On 25 Sep 2009, at 13:13, Stefan Thomas wrote:

```
```How many cents are an alteration of 10/1023?
```
```
```
I made some Haskell functions that compute these; I use Hugs <http://haskell.org/hugs/ >, but perhaps somebody can translate it to Scheme code.
```
```
For example, for E12276, LilyPond scale degree 4 (note G relative C), and interval ratio 3/2 (Just perfect fifth), the LilyPond alteration ratio with offset in cents is:
```  LilyPond> lyalt (12276) 4 (3/2)
(10 % 1023,-3.33477112590685e-05)
```
Rational number ratios are written with % in Haskell, so this is 10/1023, and the second component is -3.33477112590685e-05 cents - approximation is a bit lower than 3/2.
```
```
If one wants to know which ET is used, compute the pitch as a fraction of an octave:
```  LilyPond> lyp 4 (10/1023)
7181 % 12276
As this is fraction of an octave, the denominator gives the ET: E12276.

Hans

```

LilyPond.hs
Description: Binary data

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```