Kepler1 solves Kepler's equation by iteration.

Kepler2 solves Kepler's equation by iteration.

Kepler2a solves Kepler's equation by iteration.

Kepler2b solves Kepler's equation by iteration.

Kepler3 solves Kepler's equation by binary search.

Kepler4 returns an approximate solution to Kepler's equation.

Radius returns radius distance r for given eccentric anomaly E.

True returns true anomaly ν for given eccentric anomaly E.