Module drift 

Clock polynomial for the difference between proper time and a coordinate time.

Instantaneous proper-time rates from Spacetime use the 3+1 interval (d\tau/dt=\alpha\sqrt{1-\beta^2}). With α and β from Φ and (v), the (O(c^{-2})) expansion of that interval is IERS Conventions (2010) eqs. (10.6)–(10.7) / Ashby (2003). A Drift can also hold measured clock bias, aging, or other steering that is not that interval. See docs/relativity.md.

Structs

Drift

Quadratic polynomial for the accumulated difference between an observer’s proper time (what a real clock measures) and a chosen coordinate time such as TT, TAI, or any other Scale.