It's already been done and tried by many folks in many different contexts. Search for adaptive Just Intonation. Anyway, there's fundamental issues this approac

It's already been done and tried by many folks in many different contexts. Search for adaptive Just Intonation. Anyway, there's fundamental issues this approach can never solve. An E and G should NEVER EVER be 5/4. That would be E and G-SHARP (or E-flat and G). But this is a good example of the issue. E and G could be 6/5 or 7/6 or 19/16 or… (the first two make the most sense). So, how is the keyboard to know when I play E and G that I wanted it to be part of a C-major 4:5:6 chord versus part of an A7 4:5:6:7 chord? There's no way other than some input that can tell me or the thing adapting after-the-fact when I later add the rest of the chord. I think the best overall tuning software for keyboards is http://www.tallkite.com/alt-tuner.html http://www.tallkite.com/alt-tuner.html by the way, although adaptive stuff isn't the focus. There's many others though. Cheers