1   /* Copyright 2002-2024 CS GROUP
2    * Licensed to CS GROUP (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.propagation.numerical;
18  
19  import org.hipparchus.geometry.euclidean.threed.Vector3D;
20  
21  /** Interface summing up the contribution of several forces into orbit and mass derivatives.
22   *
23   * <p>The aim of this interface is to gather the contributions of various perturbing
24   * forces expressed as accelerations into one set of time-derivatives of
25   * {@link org.orekit.orbits.Orbit} plus one mass derivatives. It implements Gauss
26   * equations for different kind of parameters.</p>
27   * <p>An implementation of this interface is automatically provided by {@link
28   * org.orekit.propagation.integration.AbstractIntegratedPropagator integration-based
29   * propagators}, which are either semi-analytical or numerical propagators.
30   * </p>
31   * @see org.orekit.forces.ForceModel
32   * @see org.orekit.propagation.numerical.NumericalPropagator
33   * @author Luc Maisonobe
34   * @author Fabien Maussion
35   * @author V&eacute;ronique Pommier-Maurussane
36   */
37  public interface TimeDerivativesEquations {
38  
39      /** Add the contribution of the Kepler evolution.
40       * <p>Since the Kepler evolution is the most important, it should
41       * be added after all the other ones, in order to improve
42       * numerical accuracy.</p>
43       * @param mu central body gravitational constant
44       */
45      void addKeplerContribution(double mu);
46  
47      /** Add the contribution of a non-Keplerian acceleration.
48       * @param gamma acceleration vector in the same inertial frame the spacecraft state is defined in (m/s²)
49            * @since 9.0
50       */
51      void addNonKeplerianAcceleration(Vector3D gamma);
52  
53      /** Add the contribution of the flow rate (dm/dt).
54       * @param q the flow rate, must be negative (dm/dt)
55       * @exception IllegalArgumentException if flow-rate is positive
56       */
57      void addMassDerivative(double q);
58  
59  
60  }