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1   /*
2    * Licensed to the Hipparchus project under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The Hipparchus project 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    *      https://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  
18  package org.hipparchus.ode.nonstiff;
19  
20  import org.junit.Test;
21  
22  public class EulerIntegratorTest extends RungeKuttaIntegratorAbstractTest {
23  
24      protected RungeKuttaIntegrator createIntegrator(double step) {
25          return new EulerIntegrator(step);
26      }
27  
28      @Override
29      public void testMissedEndEvent() {
30          doTestMissedEndEvent(1.0e-15, 6.0e-5);
31      }
32  
33      @Override
34      public void testSanityChecks() {
35          doTestSanityChecks();
36      }
37  
38      @Override
39      public void testDecreasingSteps() {
40          doTestDecreasingSteps(1.0, 1.5, 1.0e-10);
41      }
42  
43      @Override
44      public void testSmallStep() {
45          doTestSmallStep(2.0e-4, 1.0e-3, 1.0e-12, "Euler");
46      }
47  
48      @Override
49      public void testBigStep() {
50          doTestBigStep(0.01, 0.2, 1.0e-12, "Euler");
51  
52      }
53  
54      @Override
55      public void testBackward() {
56          doTestBackward(0.45, 0.45, 1.0e-12, "Euler");
57      }
58  
59      @Override
60      public void testKepler() {
61          // Euler integrator is clearly not able to solve this problem
62          doTestKepler(881.176, 0.001);
63      }
64  
65      @Override
66      public void testStepSize() {
67          doTestStepSize(1.0e-12);
68      }
69  
70      @Override
71      public void testSingleStep() {
72          doTestSingleStep(0.21);
73      }
74  
75      @Override
76      public void testTooLargeFirstStep() {
77          doTestTooLargeFirstStep();
78      }
79  
80      @Override
81      public void testUnstableDerivative() {
82          doTestUnstableDerivative(1.0e-12);
83      }
84  
85      @Override
86      public void testDerivativesConsistency() {
87          doTestDerivativesConsistency(1.0e-10);
88      }
89  
90      @Override
91      public void testSerialization() {
92          doTestSerialization(597794, 881);
93      }
94  
95      @Test
96      public void testSecondaryEquations() {
97          doTestSecondaryEquations(4.8e-3, 5.6e-13);
98      }
99  
100 }