1   /* Copyright 2002-2016 CS Systèmes d'Information
2    * Licensed to CS Systèmes d'Information (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.forces.gravity.potential;
18  
19  import org.orekit.errors.OrekitException;
20  import org.orekit.time.AbsoluteDate;
21  import org.orekit.time.TimeStamped;
22  
23  /** Interface used to provide normalized spherical harmonics coefficients.
24   * @see GravityFieldFactory
25   * @author Luc Maisonobe
26   * @since 6.0
27   */
28  public interface NormalizedSphericalHarmonicsProvider extends SphericalHarmonicsProvider {
29  
30      /**
31       * The normalized geopotential coefficients at a specific instance in time.
32       * @see NormalizedSphericalHarmonicsProvider
33       * @see NormalizedSphericalHarmonicsProvider#onDate(AbsoluteDate)
34       * @since 6.1
35       */
36      interface NormalizedSphericalHarmonics extends TimeStamped {
37  
38          /** Get a spherical harmonic cosine coefficient.
39           * @param n degree of the coefficient
40           * @param m order of the coefficient
41           * @return normalized coefficient Cnm
42           * @exception OrekitException if the requested maximal degree or order exceeds the
43           * available degree or order
44           */
45          double getNormalizedCnm(int n, int m) throws OrekitException;
46  
47          /** Get a spherical harmonic sine coefficient.
48           * @param n degree of the coefficient
49           * @param m order of the coefficient
50           * @return normalized coefficient Snm
51           * @exception OrekitException if the requested maximal degree or order exceeds the
52           * available degree or order
53           */
54          double getNormalizedSnm(int n, int m) throws OrekitException;
55  
56      }
57  
58      /**
59       * Get the normalized spherical harmonic coefficients at a specific instance in time.
60       *
61       * @param date of evaluation
62       * @return normalized coefficients on {@code date}.
63       * @throws OrekitException on error
64       * @since 6.1
65       */
66      NormalizedSphericalHarmonics onDate(AbsoluteDate date) throws OrekitException;
67  
68  }