Are you talking about figured bass? It's probably the most obvious example for the music/math intersection, but jazz, particularly bebop uses relative intervals to great effect also (in addition to polyrhythms). I'm not sure if the guys who laid down the foundations ever formally decided that the improvisational and the logical should convene, but for a lot of people who learn jazz, the easiest way to understand how the polyrhythms and harmonies interact with each other is mathematically.A lot of baroque music is mathematically based. That was sort of the idea behind music at the time; it was seen as an extension of math. I don't remember how it actually works, but he actually had a code that translated to his name in a lot of his music. I should find some articles on that to share.