/// <summary>
/// J2积分器(惯性系中计算，无岁差章动)，右函数采用J2Gravity模型
/// <para>积分变量仅位置、速度</para>
/// <para>给position仅添加J2项右函数</para>
/// <para>RKF7(8)数值积分器，缺省绝对和相对精度皆为1e-13</para>
/// <para>Epoch属性需手动赋值</para>
/// </summary>
/// <param name="position">PropagationNewtonianPoint,单位:m,m/s</param>
/// <param name="centralBody"></param>
/// <param name="gravitationalParameter">引力常数GM(m^3/s^2)</param>
/// <param name="j2UnnormalizedValue">J2</param>
/// <param name="referenceDistance">Re(m)</param>
/// <param name="absTolerance">RKF7(8)的绝对精度</param>
/// <param name="relRolerance">RKF7(8)的相对精度</param>
public PropagatorDefinitionPureJ2(PropagationNewtonianPoint position, CentralBody centralBody, double gravitationalParameter = 3.986004418e14, double j2UnnormalizedValue = 0.001082629989052, double referenceDistance = 6378137.0, double absTolerance = 1e-13, double relRolerance = 1e-13)
{
// 中心天体的J2项引力摄动(含中心引力，中心天体的惯性系中计算)，无岁差章动
J2Gravity gravity = new J2Gravity(position.IntegrationPoint, centralBody, gravitationalParameter, j2UnnormalizedValue, referenceDistance);
// 添加右函数
position.AppliedForces.Clear();
position.AppliedForces.Add(gravity);
// 积分变量
this.IntegrationElements.Add(position);
// RKF7(8)数值积分器
RungeKuttaFehlberg78Integrator integrator = new RungeKuttaFehlberg78Integrator();
integrator.AbsoluteTolerance = absTolerance;
integrator.RelativeTolerance = relRolerance;
integrator.InitialStepSize = 60.0;
integrator.StepSizeBehavior = KindOfStepSize.Relative;
integrator.MaximumStepSize = 200.0;
integrator.MinimumStepSize = 1.0;
//* This is STK's default and truncates each step to 3 decimal places
integrator.StepTruncationOrder = -3;
this.Integrator = integrator;
}
//#########################################################################################
#region 构造函数
/// <summary>
/// 构造函数，缺省使用中心天体：地球(J2项系数为0)
/// </summary>
//public J2Gravity()
// : base(RoleOfForce.Principal, KindOfForce.NewtonianSpecificForce)
//{
// CentralBodiesFacet fromContext = CentralBodiesFacet.GetFromContext();
// this.m_centralBody = fromContext.Earth;
// this.m_gravitationalParameter = WorldGeodeticSystem1984.GravitationalParameter;
// this.J2ZonalHarmonicCoefficient = 0.0;
// this.m_referenceDistance = m_centralBody.Shape.SemimajorAxisLength;
//}
/// <summary>
/// 构造函数，缺省使用中心天体：地球(J2项系数为0)
/// </summary>
/// <param name="targetPoint">计算引力的瞬时点(位置、速度)</param>
//public J2Gravity(Point targetPoint)
// : this()
//{
// this.m_targetPoint = targetPoint;
//}
/// <summary>
/// 构造函数，从已有对象复制
/// </summary>
/// <param name="existingInstance">已有对象</param>
/// <param name="context">A CopyContext that controls the depth of the copy.</param>
protected J2Gravity(J2Gravity existingInstance, CopyContext context)
: base(existingInstance, context)
{
this.m_centralBody = context.UpdateReference <CentralBody>(existingInstance.m_centralBody);
this.m_gravitationalParameter = existingInstance.m_gravitationalParameter;
this.m_ignorePartials = existingInstance.m_ignorePartials;
this.m_targetPoint = context.UpdateReference <Point>(existingInstance.m_targetPoint);
this.m_j2ZonalHarmonicCoefficient = existingInstance.m_j2ZonalHarmonicCoefficient;
this.m_referenceDistance = existingInstance.m_referenceDistance;
}
/// <summary>
/// 计算给定时刻的J2项引力(在坐标轴)
/// </summary>
/// <param name="date"></param>
/// <returns></returns>
public override Cartesian Evaluate(JulianDate date)
{
return(J2Gravity.CalculateAcceleration(this.m_position.Evaluate(date), this.m_gravity, this.m_j2ZonalHarmonicCoefficient, this.m_referenceDistance));
}