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1   /*
2    * Licensed to the Apache Software Foundation (ASF) 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 ASF 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  
18  /*
19   * This is not the original file distributed by the Apache Software Foundation
20   * It has been modified by the Hipparchus project
21   */
22  
23  package org.hipparchus.migration.ode;
24  
25  import org.hipparchus.exception.MathIllegalArgumentException;
26  import org.hipparchus.exception.MathIllegalStateException;
27  import org.hipparchus.ode.OrdinaryDifferentialEquation;
28  
29  
30  
31  /** This interface represents a first order differential equations set.
32   *
33   * <p>This interface should be implemented by all real first order
34   * differential equation problems before they can be handled by the
35   * integrators {@link org.hipparchus.ode.ODEIntegrator#integrate} method.</p>
36   *
37   * <p>A first order differential equations problem, as seen by an
38   * integrator is the time derivative <code>dY/dt</code> of a state
39   * vector <code>Y</code>, both being one dimensional arrays. From the
40   * integrator point of view, this derivative depends only on the
41   * current time <code>t</code> and on the state vector
42   * <code>Y</code>.</p>
43   *
44   * <p>For real problems, the derivative depends also on parameters
45   * that do not belong to the state vector (dynamical model constants
46   * for example). These constants are completely outside of the scope
47   * of this interface, the classes that implement it are allowed to
48   * handle them as they want.</p>
49   *
50   * @see org.hipparchus.ode.ODEIntegrator
51   * @see org.hipparchus.ode.FirstOrderConverter
52   * @see SecondOrderDifferentialEquations
53   * @deprecated as of 1.0, replaced with {@link OrdinaryDifferentialEquation}
54   */
55  @Deprecated
56  public interface FirstOrderDifferentialEquations extends OrdinaryDifferentialEquation {
57  
58      /** {@inheritDoc}
59       * <p>
60       * The default implementation calls {@link #computeDerivatives(double, double[], double[])}.
61       * </p>
62       */
63      @Override
64      default double[] computeDerivatives(double t, double[] y) {
65          final double[] yDot = new double[y.length];
66          computeDerivatives(t, y, yDot);
67          return yDot;
68      }
69  
70      /** Get the current time derivative of the state vector.
71       * @param t current value of the independent <I>time</I> variable
72       * @param y array containing the current value of the state vector
73       * @param yDot placeholder array where to put the time derivative of the state vector
74       * @exception MathIllegalStateException if the number of functions evaluations is exceeded
75       * @exception MathIllegalArgumentException if arrays dimensions do not match equations settings
76       */
77      void computeDerivatives(double t, double[] y, double[] yDot)
78          throws MathIllegalArgumentException, MathIllegalStateException;
79  
80  }