# transratio question

barry threw

Nov 13 2008 | 4:40 am

Hello friends,

In many example patches, like the transposition playground, I see a
sub-patcher called "transratio".

It is an expr with the following formula... ((440. * exp(.057762265 *
$f1))* 0.002273) that serves the purpose of turning pitch changes into
transposition multipliers.

The issue is that multiplying by 0.002273 is the same as dividing by
440. so you end up multiplying and then dividing by 440.

In the phase vocoder example by Dudas and Cort on the c74 site, this
same patcher is used, but its even more explicit:
expr ((440. * exp(.057762265 * $f1))/ 440.)

Now, Les and Richard are two gentlemen that history tells me don't do
things for no reason. However, I can't figure out why on earth this
formula multiplies and then divides by 440. Taking those two
statements out seems to yield the same results.

Any help anyone?

barry threw
Media Art and Technology

San Francisco, CA
Work: 857-544-3967
Email: bthrew (at) gmail (dot) com
Web: www.barrythrew.com