1   /* Copyright 2002-2025 CS GROUP
2    * Licensed to CS GROUP (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.conversion;
18  
19  import org.hipparchus.CalculusFieldElement;
20  import org.hipparchus.Field;
21  import org.hipparchus.exception.LocalizedCoreFormats;
22  import org.hipparchus.exception.MathIllegalArgumentException;
23  import org.hipparchus.ode.AbstractFieldIntegrator;
24  
25  /**
26   * Abstract class for integrator builder using fixed step size.
27   *
28   * @param <T> Type of the field elements
29   *
30   * @author Vincent Cucchietti
31   */
32  public abstract class AbstractFixedStepFieldIntegratorBuilder<T extends CalculusFieldElement<T>, W  extends AbstractFieldIntegrator<T>>
33          extends FieldAbstractIntegratorBuilder<T, W> {
34  
35      /** Step size (s). */
36      private final double step;
37  
38      /** Step size (s). */
39      private T fieldStep;
40  
41      /**
42       * Constructor.
43       *
44       * @param step step size (s)
45       */
46      protected AbstractFixedStepFieldIntegratorBuilder(final double step) {
47          // Check that given step size is strictly positive
48          checkStep(step);
49  
50          this.step = step;
51      }
52  
53      /**
54       * Constructor using a "fielded" step.
55       * <p>
56       * <b>WARNING : Given "fielded" step must be using the same field as the one that will be used when calling
57       * {@link #buildIntegrator}</b>
58       *
59       * @param step step size (s)
60       */
61      protected AbstractFixedStepFieldIntegratorBuilder(final T step) {
62          this(step.getReal());
63          this.fieldStep = step;
64      }
65  
66      /**
67       * Check that given step size is not equal to 0.
68       *
69       * @param stepToCheck step size (s) to check
70       */
71      protected void checkStep(final double stepToCheck) {
72          if (stepToCheck == 0) {
73              throw new MathIllegalArgumentException(LocalizedCoreFormats.ZERO_NOT_ALLOWED, stepToCheck);
74          }
75      }
76  
77      /**
78       * Get "fielded" step size (s).
79       *
80       * @param field field to which the element belong
81       *
82       * @return "fielded" step size (s)
83       */
84      protected T getFieldStep(final Field<T> field) {
85          return fieldStep != null ? fieldStep : field.getZero().newInstance(step);
86      }
87  
88      /**
89       * Getter for the step size (s).
90       * @return step size
91       * @since 13.0
92       */
93      protected double getStep() {
94          return step;
95      }
96  }