001 /*
002 * This file is part of McIDAS-V
003 *
004 * Copyright 2007-2013
005 * Space Science and Engineering Center (SSEC)
006 * University of Wisconsin - Madison
007 * 1225 W. Dayton Street, Madison, WI 53706, USA
008 * https://www.ssec.wisc.edu/mcidas
009 *
010 * All Rights Reserved
011 *
012 * McIDAS-V is built on Unidata's IDV and SSEC's VisAD libraries, and
013 * some McIDAS-V source code is based on IDV and VisAD source code.
014 *
015 * McIDAS-V is free software; you can redistribute it and/or modify
016 * it under the terms of the GNU Lesser Public License as published by
017 * the Free Software Foundation; either version 3 of the License, or
018 * (at your option) any later version.
019 *
020 * McIDAS-V is distributed in the hope that it will be useful,
021 * but WITHOUT ANY WARRANTY; without even the implied warranty of
022 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
023 * GNU Lesser Public License for more details.
024 *
025 * You should have received a copy of the GNU Lesser Public License
026 * along with this program. If not, see http://www.gnu.org/licenses.
027 */
028 // Shawn E. Gano
029 /**
030 * =====================================================================
031 * Copyright (C) 2009 Shawn E. Gano
032 *
033 * This file is part of JSatTrak.
034 *
035 * JSatTrak is free software: you can redistribute it and/or modify
036 * it under the terms of the GNU Lesser General Public License as published by
037 * the Free Software Foundation, either version 3 of the License, or
038 * (at your option) any later version.
039 *
040 * JSatTrak is distributed in the hope that it will be useful,
041 * but WITHOUT ANY WARRANTY; without even the implied warranty of
042 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
043 * GNU Lesser General Public License for more details.
044 *
045 * You should have received a copy of the GNU Lesser General Public License
046 * along with JSatTrak. If not, see <http://www.gnu.org/licenses/>.
047 * =====================================================================
048 */
049
050 package edu.wisc.ssec.mcidasv.data.adde.sgp4;
051
052 /**
053 * Various Math functions; many of them for vector and matrix operations for 3 dimensions.
054 */
055 public class MathUtils
056 {
057
058 // vector 2-norm
059 /**
060 * vector 2-norm
061 *
062 * @param a vector of length 3
063 * @return norm(a)
064 */
065 public static double norm(double[] a)
066 {
067 double c = 0.0;
068
069 for(int i=0;i<a.length;i++)
070 {
071 c += a[i]*a[i];
072 }
073
074 return Math.sqrt(c);
075 }
076
077 // dot product for 3D vectors
078 /**
079 * dot product for 3D vectors
080 *
081 * @param a 3x1 vector
082 * @param b 3x1 vector
083 * @return a dot b
084 */
085 public static double dot(double[] a, double[] b)
086 {
087 double c =0;;
088
089 for (int i = 0; i < 3; i++) // row
090 {
091 c += a[i]*b[i];
092 }
093
094 return c;
095
096 } // mult 3x3 matrices
097
098 /**
099 * multiply two matrices 3x3
100 *
101 * @param a 3x3 matrix
102 * @param b 3x3 matrix
103 * @return a x b
104 */
105 public static double[][] mult(double[][] a, double[][] b)
106 {
107 double[][] c = new double[3][3];
108
109 for (int i = 0; i < 3; i++) // row
110 {
111 for (int j = 0; j < 3; j++) // col
112 {
113 c[i][j] = 0.0;
114 for (int k = 0; k < 3; k++)
115 {
116 c[i][j] += a[i][k] * b[k][j];
117 }
118 }
119 }
120
121 return c;
122
123 } // mult 3x3 matrices
124
125 /**
126 * vector subtraction
127 *
128 * @param a vector of length 3
129 * @param b vector of length 3
130 * @return a-b
131 */
132 public static double[] sub(double[] a, double[] b)
133 {
134 double[] c = new double[3];
135 for(int i=0;i<3;i++)
136 {
137 c[i] = a[i] - b[i];
138 }
139
140 return c;
141 }
142 }