/// <summary>
/// PreciseOrbital Velocy in polar coordinates
///
/// </summary>
/// <returns>item1 is speed, item2 angle</returns>
/// <param name="orbit">Orbit.</param>
/// <param name="atDateTime">At date time.</param>
public static (double speed, double angle) InstantaneousOrbitalVelocityPolarCoordinate(OrbitDB orbit, DateTime atDateTime)
{
var position = GetPosition_AU(orbit, atDateTime);
var sma = orbit.SemiMajorAxis;
if (orbit.GravitationalParameter == 0 || sma == 0)
{
return(0, 0); //so we're not returning NaN;
}
var sgp = orbit.GravitationalParameterAU;
double e = orbit.Eccentricity;
double trueAnomaly = GetTrueAnomaly(orbit, atDateTime);
double loAN = Angle.ToRadians(orbit.LongitudeOfAscendingNode);
double aoP = Angle.ToRadians(orbit.ArgumentOfPeriapsis);
double inclination = Angle.ToRadians(orbit.Inclination);
var loP = OrbitMath.GetLongditudeOfPeriapsis(inclination, aoP, loAN);
(double speed, double angle)polar = OrbitMath.InstantaneousOrbitalVelocityPolarCoordinate(sgp, position, sma, e, trueAnomaly);
polar.angle += loP;
return(polar);
}