reparam
Reparameterizes \(\left(x, \frac{dx}{du}, \frac{d^2x}{du^2}, \ldots, \frac{d^{n - 1} x}{du^{n - 1}}\right)\) into \(\left(x, \frac{dx}{dt}, \frac{d^2x}{dt^2}, \ldots, \frac{d^{n - 1} x}{dt^{n - 1}}\right)\) using oldParam and the chain rule.
Parameters
old
\(\left(u, \frac{du}{dt}, \frac{d^2u}{dt^2}, \ldots, \frac{d^{n - 1} u}{dt^{n - 1}}\right)\)