TimeDerivativesEquations (OREKIT 12.1.2 API)

```
public interface TimeDerivativesEquations
```
Interface summing up the contribution of several forces into orbit and mass derivatives.
The aim of this interface is to gather the contributions of various perturbing forces expressed as accelerations into one set of time-derivatives of Orbit plus one mass derivatives. It implements Gauss equations for different kind of parameters.

An implementation of this interface is automatically provided by integration-based propagators, which are either semi-analytical or numerical propagators.

Author:

Luc Maisonobe, Fabien Maussion, Véronique Pommier-Maurussane

See Also:

ForceModel, NumericalPropagator

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`addKeplerContribution(double mu)`	Add the contribution of the Kepler evolution.
`void`	`addMassDerivative(double q)`	Add the contribution of the flow rate (dm/dt).
`void`	`addNonKeplerianAcceleration(Vector3D gamma)`	Add the contribution of a non-Keplerian acceleration.

- Method Detail
  - addKeplerContribution
```
void addKeplerContribution(double mu)
```
    Add the contribution of the Kepler evolution.
    Since the Kepler evolution is the most important, it should be added after all the other ones, in order to improve numerical accuracy.
    
    Parameters:
    
    mu - central body gravitational constant
  - addNonKeplerianAcceleration
```
void addNonKeplerianAcceleration(Vector3D gamma)
```
    Add the contribution of a non-Keplerian acceleration.
    
    Parameters:
    
    gamma - acceleration vector in the same inertial frame the spacecraft state is defined in (m/s²)
    
    Since:
    
    9.0
  - addMassDerivative
```
void addMassDerivative(double q)
```
    Add the contribution of the flow rate (dm/dt).
    
    Parameters:
    
    q - the flow rate, must be negative (dm/dt)
    
    Throws:
    
    IllegalArgumentException - if flow-rate is positive