Avoid interpolation, find closest time

[md-arif-shaikh]

To get times $t_{\mathrm{in}}$ for input frequencies $f_{\mathrm{in}}$ from the $\langle \omega_{22}\rangle-t$ relation, instead of using interpolant $t=t(\langle\omega_{22}\rangle)$, just find the closet times that satisfies $\langle\omega_{22}\rangle (t_{\mathrm{in}}) = f_{\mathrm{in}}$ using np.argmin.