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17 package org.orekit.forces.gravity.potential;
18
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20 import org.hipparchus.util.FastMath;
21 import org.hipparchus.util.Precision;
22 import org.junit.Assert;
23 import org.junit.Test;
24 import org.orekit.Utils;
25 import org.orekit.errors.OrekitException;
26 import org.orekit.forces.gravity.potential.NormalizedSphericalHarmonicsProvider.NormalizedSphericalHarmonics;
27 import org.orekit.forces.gravity.potential.UnnormalizedSphericalHarmonicsProvider.UnnormalizedSphericalHarmonics;
28 import org.orekit.time.AbsoluteDate;
29 import org.orekit.utils.Constants;
30
31 public class EGMFormatReaderTest {
32
33 @Test
34 public void testReadNormalized() {
35 Utils.setDataRoot("potential");
36 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("egm96_to5.ascii", true));
37 NormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getNormalizedProvider(5, 5);
38 NormalizedSphericalHarmonics harmonics = provider.onDate(AbsoluteDate.FUTURE_INFINITY);
39 Assert.assertEquals(TideSystem.TIDE_FREE, provider.getTideSystem());
40 Assert.assertEquals( 0.957254173792E-06, harmonics.getNormalizedCnm(3, 0), 1.0e-15);
41 Assert.assertEquals( 0.174971983203E-06, harmonics.getNormalizedCnm(5, 5), 1.0e-15);
42 Assert.assertEquals( 0.0, harmonics.getNormalizedSnm(4, 0), 1.0e-15);
43 Assert.assertEquals( 0.308853169333E-06, harmonics.getNormalizedSnm(4, 4), 1.0e-15);
44 Assert.assertEquals(-0.295301647654E-06, harmonics.getNormalizedCnm(5, 4), 1.0e-15);
45 }
46
47 @Test
48 public void testReadUnnormalized() {
49 Utils.setDataRoot("potential");
50 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("egm96_to5.ascii", true));
51 UnnormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getUnnormalizedProvider(5, 5);
52 UnnormalizedSphericalHarmonics harmonics = provider.onDate(AbsoluteDate.FUTURE_INFINITY);
53 Assert.assertEquals(TideSystem.TIDE_FREE, provider.getTideSystem());
54 int maxUlps = 1;
55 checkValue(harmonics.getUnnormalizedCnm(3, 0), 3, 0, 0.957254173792E-06, maxUlps);
56 checkValue(harmonics.getUnnormalizedCnm(5, 5), 5, 5, 0.174971983203E-06, maxUlps);
57 checkValue(harmonics.getUnnormalizedSnm(4, 0), 4, 0, 0.0, maxUlps);
58 checkValue(harmonics.getUnnormalizedSnm(4, 4), 4, 4, 0.308853169333E-06, maxUlps);
59
60 double a = (-0.295301647654E-06);
61 double b = 9*8*7*6*5*4*3*2;
62 double c = 2*11/b;
63 double result = a*FastMath.sqrt(c);
64
65 Assert.assertEquals(result, harmonics.getUnnormalizedCnm(5, 4), 1.0e-20);
66
67 a = -0.188560802735E-06;
68 b = 8*7*6*5*4*3*2;
69 c=2*9/b;
70 result = a*FastMath.sqrt(c);
71 Assert.assertEquals(result, harmonics.getUnnormalizedCnm(4, 4), 1.0e-20);
72
73 Assert.assertEquals(1.0826266835531513e-3, -harmonics.getUnnormalizedCnm(2, 0), 1.0e-20);
74
75 }
76
77 @Test
78 @Deprecated
79 public void testDeprecated() throws OrekitException {
80 Utils.setDataRoot("potential");
81 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("egm96_to5.ascii", true));
82 UnnormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getUnnormalizedProvider(5, 5);
83 Assert.assertNull(provider.getReferenceDate());
84 Assert.assertEquals(0, provider.getOffset(AbsoluteDate.J2000_EPOCH), Precision.SAFE_MIN);
85 Assert.assertEquals(0, provider.getOffset(AbsoluteDate.MODIFIED_JULIAN_EPOCH), Precision.SAFE_MIN);
86 }
87
88 @Test
89 public void testReadLimits() {
90 Utils.setDataRoot("potential");
91 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("egm96_to5.ascii", true));
92 UnnormalizedSphericalHarmonicsProvider provider = GravityFieldFactory.getUnnormalizedProvider(3, 2);
93 UnnormalizedSphericalHarmonics harmonics = provider.onDate(null);
94 try {
95 harmonics.getUnnormalizedCnm(3, 3);
96 Assert.fail("an exception should have been thrown");
97 } catch (OrekitException oe) {
98
99 } catch (Exception e) {
100 Assert.fail("wrong exception caught: " + e.getLocalizedMessage());
101 }
102 try {
103 harmonics.getUnnormalizedCnm(4, 2);
104 Assert.fail("an exception should have been thrown");
105 } catch (OrekitException oe) {
106
107 } catch (Exception e) {
108 Assert.fail("wrong exception caught: " + e.getLocalizedMessage());
109 }
110 harmonics.getUnnormalizedCnm(3, 2);
111 Assert.assertEquals(3, provider.getMaxDegree());
112 Assert.assertEquals(2, provider.getMaxOrder());
113 }
114
115 @Test(expected=OrekitException.class)
116 public void testCorruptedFile1() {
117 Utils.setDataRoot("potential");
118 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("corrupted-1-egm96_to5", false));
119 GravityFieldFactory.getUnnormalizedProvider(5, 5);
120 }
121
122 @Test(expected=OrekitException.class)
123 public void testCorruptedFile2() {
124 Utils.setDataRoot("potential");
125 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("corrupted-2-egm96_to5", false));
126 GravityFieldFactory.getUnnormalizedProvider(5, 5);
127 }
128
129 @Test(expected=OrekitException.class)
130 public void testCorruptedFile3() {
131 Utils.setDataRoot("potential");
132 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("corrupted-3-egm96_to5", false));
133 GravityFieldFactory.getUnnormalizedProvider(5, 5);
134 }
135
136 @Test
137 public void testZeroTidePattern1() {
138 Utils.setDataRoot("potential");
139 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("dummy_egm2008", true));
140 Assert.assertEquals(TideSystem.ZERO_TIDE,
141 GravityFieldFactory.getUnnormalizedProvider(5, 5).getTideSystem());
142 }
143
144 @Test
145 public void testZeroTidePattern2() {
146 Utils.setDataRoot("potential");
147 GravityFieldFactory.addPotentialCoefficientsReader(new EGMFormatReader("dummy_zerotide", true));
148 Assert.assertEquals(TideSystem.ZERO_TIDE,
149 GravityFieldFactory.getUnnormalizedProvider(5, 5).getTideSystem());
150 }
151
152 @Test
153 public void testWgs84CoefficientOverride()
154 {
155 final double epsilon = Precision.EPSILON;
156
157 Utils.setDataRoot("potential");
158 EGMFormatReader egm96Reader = new EGMFormatReader("egm96_to5.ascii", true);
159 GravityFieldFactory.addPotentialCoefficientsReader(egm96Reader);
160 GravityFieldFactory.getNormalizedProvider(5, 5);
161 Assert.assertEquals(Constants.EGM96_EARTH_EQUATORIAL_RADIUS, egm96Reader.getAe(), epsilon);
162 Assert.assertEquals(Constants.EGM96_EARTH_MU, egm96Reader.getMu(), epsilon);
163
164 Utils.setDataRoot("potential");
165 EGMFormatReader wgs84Egm96Reader = new EGMFormatReader("egm96_to5.ascii", true, true);
166 GravityFieldFactory.addPotentialCoefficientsReader(wgs84Egm96Reader);
167 GravityFieldFactory.getNormalizedProvider(5, 5);
168 Assert.assertEquals(Constants.WGS84_EARTH_EQUATORIAL_RADIUS, wgs84Egm96Reader.getAe(), epsilon);
169 Assert.assertEquals(Constants.WGS84_EARTH_MU, wgs84Egm96Reader.getMu(), epsilon);
170
171 }
172
173 private void checkValue(final double value, final int n, final int m,
174 final double constant, final int maxUlps)
175 {
176 double factor = GravityFieldFactory.getUnnormalizationFactors(n, m)[n][m];
177 double normalized = factor * constant;
178 double epsilon = maxUlps * FastMath.ulp(normalized);
179 Assert.assertEquals(normalized, value, epsilon);
180 }
181
182 }