Wave Digital Mass-Spring Oscillator

Convert force waves to root-power waves:

$$\begin{eqnarray*} \tilde{f}^{+}_i&\isdef & \frac{f^{{+}}_i}{\sqrt{R_i}} \\ [1em] \tilde{v}^{+}_i &\isdef & v^{+}_i \cdot \sqrt{R_i} \end{eqnarray*}$$

where $R_i=$ wave impedance in waveguide $i$.