HansenUtilities.java

  1. /* Copyright 2002-2018 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.propagation.semianalytical.dsst.utilities.hansen;

  19. import org.hipparchus.analysis.polynomials.PolynomialFunction;

  21. /**
  22.  * Utilities class.
  23.  *
  24.  * @author Lucian Barbulescu
  25.  */
  26. public class HansenUtilities {

  28.     /** 1 represented as a polynomial. */
  29.     public static final PolynomialFunction ONE = new PolynomialFunction(new double[] {
  30.         1
  31.     });

  33.     /** 0 represented as a polynomial. */
  34.     public static final PolynomialFunction ZERO = new PolynomialFunction(new double[] {
  35.         0
  36.     });

  38.     /** Private constructor as class is a utility.
  39.      */
  40.     private HansenUtilities() {
  41.     }

  43.     /**
  44.      * Build the identity matrix of order 2.
  45.      *
  46.      * <pre>
  47.      *       / 1   0 \
  48.      *  I₂ = |       |
  49.      *       \ 0   1 /
  50.      * </pre>
  51.      *
  52.      * @return the identity matrix of order 2
  53.      */
  54.     public static final PolynomialFunctionMatrix buildIdentityMatrix2() {
  55.         final PolynomialFunctionMatrix matrix = new PolynomialFunctionMatrix(2);
  56.         matrix.setMatrix(new PolynomialFunction[][] {
  57.             {
  58.                 ONE,  ZERO
  59.             },
  60.             {
  61.                 ZERO, ONE
  62.             }
  63.         });
  64.         return matrix;
  65.     }

  67.     /**
  68.      * Build the empty matrix of order 2.
  69.      *
  70.      * <pre>
  71.      *       / 0   0 \
  72.      *  E₂ = |       |
  73.      *       \ 0   0 /
  74.      * </pre>
  75.      *
  76.      * @return the identity matrix of order 2
  77.      */
  78.     public static final PolynomialFunctionMatrix buildZeroMatrix2() {
  79.         final PolynomialFunctionMatrix matrix = new PolynomialFunctionMatrix(2);
  80.         matrix.setMatrix(new PolynomialFunction[][] {
  81.             {
  82.                 ZERO, ZERO
  83.             },
  84.             {
  85.                 ZERO, ZERO
  86.             }
  87.         });
  88.         return matrix;
  89.     }


  92.     /**
  93.      * Build the identity matrix of order 4.
  94.      *
  95.      * <pre>
  96.      *       / 1  0  0  0 \
  97.      *       |            |
  98.      *       | 0  1  0  0 |
  99.      *  I₄ = |            |
  100.      *       | 0  0  1  0 |
  101.      *       |            |
  102.      *       \ 0  0  0  1 /
  103.      * </pre>
  104.      *
  105.      * @return the identity matrix of order 4
  106.      */
  107.     public static final PolynomialFunctionMatrix buildIdentityMatrix4() {
  108.         final PolynomialFunctionMatrix matrix = new PolynomialFunctionMatrix(4);
  109.         matrix.setMatrix(new PolynomialFunction[][] {
  110.             {
  111.                 ONE,  ZERO, ZERO, ZERO
  112.             },
  113.             {
  114.                 ZERO, ONE,  ZERO, ZERO
  115.             },
  116.             {
  117.                 ZERO, ZERO, ONE,  ZERO
  118.             },
  119.             {
  120.                 ZERO, ZERO, ZERO, ONE
  121.             }
  122.         });
  123.         return matrix;
  124.     }

  126.     /**
  127.      * Build the empty matrix of order 4.
  128.      *
  129.      * <pre>
  130.      *       / 0  0  0  0 \
  131.      *       |            |
  132.      *       | 0  0  0  0 |
  133.      *  E₄ = |            |
  134.      *       | 0  0  0  0 |
  135.      *       |            |
  136.      *       \ 0  0  0  0 /
  137.      * </pre>
  138.      *
  139.      * @return the identity matrix of order 4
  140.      */
  141.     public static final PolynomialFunctionMatrix buildZeroMatrix4() {
  142.         final PolynomialFunctionMatrix matrix = new PolynomialFunctionMatrix(4);
  143.         matrix.setMatrix(new PolynomialFunction[][] {
  144.             {
  145.                 ZERO, ZERO, ZERO, ZERO
  146.             },
  147.             {
  148.                 ZERO, ZERO, ZERO, ZERO
  149.             },
  150.             {
  151.                 ZERO, ZERO, ZERO, ZERO
  152.             },
  153.             {
  154.                 ZERO, ZERO, ZERO, ZERO
  155.             }
  156.         } );
  157.         return matrix;
  158.     }

  160. }
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