1   /* Copyright 2002-2021 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.sampling;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.orekit.propagation.FieldSpacecraftState;
21  import org.orekit.time.FieldAbsoluteDate;
22  
23  /** This interface is a space-dynamics aware step interpolator.
24   *
25   * <p>It mirrors the <code>StepInterpolator</code> interface from <a
26   * href="http://commons.apache.org/math/"> commons-math</a> but
27   * provides a space-dynamics interface to the methods.</p>
28   * @author Luc Maisonobe
29   */
30  public interface FieldOrekitStepInterpolator<T extends CalculusFieldElement<T>> {
31  
32      /**
33       * Get the state at previous grid point date.
34       * @return state at previous grid point date
35       */
36      FieldSpacecraftState<T> getPreviousState();
37  
38      /**
39       * Get the state at previous grid point date.
40       * @return state at previous grid point date
41       */
42      FieldSpacecraftState<T> getCurrentState();
43  
44      /** Get the state at interpolated date.
45       * @param date date of the interpolated state
46       * @return state at interpolated date
47            * the date
48       */
49      FieldSpacecraftState<T> getInterpolatedState(FieldAbsoluteDate<T> date);
50  
51      /** Check is integration direction is forward in date.
52       * @return true if integration is forward in date
53       */
54      boolean isForward();
55  
56      /** Create a new restricted version of the instance.
57       * <p>
58       * The instance is not changed at all.
59       * </p>
60       * @param newPreviousState start of the restricted step
61       * @param newCurrentState end of the restricted step
62       * @return restricted version of the instance
63       * @see #getPreviousState()
64       * @see #getCurrentState()
65       * @since 11.0
66       */
67      FieldOrekitStepInterpolator<T> restrictStep(FieldSpacecraftState<T> newPreviousState, FieldSpacecraftState<T> newCurrentState);
68  
69  }