I was really in to Supercollider a long time ago, and I remember there were synths floating around on the mailing list that included big arrays of weird looking

I was really in to Supercollider a long time ago, and I remember there were synths floating around on the mailing list that included big arrays of weird looking values, and they somehow made drum sounds. My brain is remembering that they were called eigenvalues, but I tried searching and didn't find much. No idea how someone figured out or calculated the values. I think they were impractical to calculate at runtime in supercollider.