hi all -

i need to convert a frequency (Hz) to a pitch number in equal temperament. if i were using 440Hz tuning, this would be easy - i'd just use [ftom].

but i need this patch to work with ANY reference pitch, not just A4=440Hz.

the formula to do this is (i think!):

p = 12.Log2(f/R)

where p = note pitch number (A4 = 0)
f = frequency (Hz)
R = reference pitch (eg, A4 = 442 Hz)

the problem here is that i have no idea how to do a binary logarithm (log2) calculation in pd.

anyone have any ideas how to do this??

cheers,
jon.

[f freq] [f ref]
| |
| |
[expr 12*(log($f1/$f2)/log(2))]
|
|
[f result]

(http://en.wikipedia.org/wiki/Logarithm#Change_of_base)

well, i can't say i can get my head around logarithms any better now (ok, at all!)... but that works a treat.

thanks nau!