1   /* Copyright 2011-2012 Space Applications Services
2    * Licensed to CS Communication & Systèmes (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.models.earth;
18  
19  import java.io.Serial;
20  import java.io.Serializable;
21  import java.text.DecimalFormat;
22  import java.text.NumberFormat;
23  
24  import org.hipparchus.geometry.euclidean.threed.Vector3D;
25  import org.hipparchus.util.FastMath;
26  import org.orekit.utils.units.UnitsConverter;
27  
28  /** Contains the elements to represent a magnetic field at a single point.
29   * @author Thomas Neidhart
30   */
31  public class GeoMagneticElements implements Serializable {
32  
33      /** Serializable UID. */
34      @Serial
35      private static final long serialVersionUID = 1881493738280586855L;
36  
37      /** The magnetic field vector (East=X, North=Y, Nadir=Z). */
38      private final Vector3D b;
39  
40      /** The magnetic inclination in radians. */
41      private final double inclination;
42  
43      /** The magnetic declination in radians. */
44      private final double declination;
45  
46      /** The magnetic total intensity, in Teslas. */
47      private final double totalIntensity;
48  
49      /** The magnetic horizontal intensity, in Teslas. */
50      private final double horizontalIntensity;
51  
52      /** Construct a new element with the given field vector. The other elements
53       * of the magnetic field are calculated from the field vector.
54       * @param b the magnetic field vector
55       */
56      public GeoMagneticElements(final Vector3D b) {
57          this.b = new Vector3D(UnitsConverter.NANO_TESLAS_TO_TESLAS.getFrom().getScale(), b);
58  
59          final double intensityNanoTesla = FastMath.hypot(b.getX(), b.getY());
60          horizontalIntensity = UnitsConverter.NANO_TESLAS_TO_TESLAS.convert(intensityNanoTesla);
61          totalIntensity = UnitsConverter.NANO_TESLAS_TO_TESLAS.convert(b.getNorm());
62          declination = FastMath.atan2(b.getY(), b.getX());
63          inclination = FastMath.atan2(b.getZ(), intensityNanoTesla);
64      }
65  
66      /** Returns the magnetic field vector in Tesla.
67       * @return the magnetic field vector in Tesla
68       */
69      public Vector3D getFieldVector() {
70          return b;
71      }
72  
73      /** Returns the inclination of the magnetic field in radians.
74       * @return the inclination (dip) in radians
75       */
76      public double getInclination() {
77          return inclination;
78      }
79  
80      /** Returns the declination of the magnetic field in radians.
81       * @return the declination (dec) in radians
82       */
83      public double getDeclination() {
84          return declination;
85      }
86  
87      /** Returns the total intensity of the magnetic field (= norm of the field vector).
88       * @return the total intensity in Tesla
89       */
90      public double getTotalIntensity() {
91          return totalIntensity;
92      }
93  
94      /** Returns the horizontal intensity of the magnetic field (= norm of the
95       * vector in the plane spanned by the x/y components of the field vector).
96       * @return the horizontal intensity in Tesla
97       */
98      public double getHorizontalIntensity() {
99          return horizontalIntensity;
100     }
101 
102     @Override
103     public String toString() {
104         final NumberFormat f = NumberFormat.getInstance();
105         final DecimalFormat d = new DecimalFormat("0.######E0");
106         final StringBuilder sb = new StringBuilder();
107         sb.append("MagneticField[");
108         sb.append("B=");
109         sb.append(b.toString(d));
110         sb.append(",H=");
111         sb.append(d.format(getHorizontalIntensity()));
112         sb.append(",F=");
113         sb.append(d.format(getTotalIntensity()));
114         sb.append(",I=");
115         sb.append(f.format(getInclination()));
116         sb.append(",D=");
117         sb.append(f.format(getDeclination()));
118         sb.append("]");
119         return sb.toString();
120     }
121 }