However, if we refer to Wikipedia, we need to know the semi-major axis to calculate the semi-latus rectum. But the semi-major axis is only defined for circles and ellipses, if I am not getting it wrong.radius = semi-latus rectum / (1 + eccentricity * cos (true anomaly)).

So assume I am in a parabolic or hyperbolic orbit and I know my current location, velocity, true anomaly, specific energy, eccentricity and the periapsis radius. How can I calculate the semi-latus rectum from these values in order to be able to calculate future locations?

Thank you!