1   /* Copyright 2002-2025 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.forces.gravity.potential;
18  
19  import org.orekit.time.AbsoluteDate;
20  import org.orekit.time.TimeStamped;
21  
22  /** Interface used to provide raw spherical harmonics coefficients.
23   * <p>
24   * This interface is intended to be used only as the workhorse for
25   * either {@link NormalizedSphericalHarmonicsProvider} or
26   * {@link SphericalHarmonicsProvider} implementations.
27   * </p>
28   * @see GravityFields
29   * @author Luc Maisonobe
30   * @since 6.0
31   */
32  public interface RawSphericalHarmonicsProvider extends SphericalHarmonicsProvider {
33  
34      /**
35       * The raw spherical harmonics at a particular instant.
36       *
37       * @see RawSphericalHarmonicsProvider#onDate(AbsoluteDate)
38       */
39      interface RawSphericalHarmonics extends TimeStamped {
40  
41          /** Get a spherical harmonic cosine coefficient.
42           * @param n degree of the coefficient
43           * @param m order of the coefficient
44           * @return raw coefficient Cnm
45           */
46          double getRawCnm(int n, int m);
47  
48          /** Get a spherical harmonic sine coefficient.
49           * @param n degree of the coefficient
50           * @param m order of the coefficient
51           * @return raw coefficient Snm
52           */
53          double getRawSnm(int n, int m);
54  
55      }
56  
57      /**
58       * Get the raw spherical harmonic coefficients on a specific date.
59       * @param date to evaluate the spherical harmonics
60       * @return the raw spherical harmonics on {@code date}.
61       */
62      RawSphericalHarmonics onDate(AbsoluteDate date);
63  
64  }