Predefined frequency relationship patterns.
Integer harmonics: f, 2f, 3f, 4f...
Bell-like: f, 2.76f, 5.40f, 8.93f, 13.34f...
Piano-like stiffness: f, 2.01f, 3.02f, 4.04f...
User-provided frequency ratios.
Definition at line 64 of file ModalNetwork.hpp.