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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.math3.ode;
import org.apache.commons.math3.RealFieldElement;
/** This interface represents a first order differential equations set.
*
* This interface should be implemented by all real first order
* differential equation problems before they can be handled by the
* integrators {@link FirstOrderIntegrator#integrate} method.
*
* A first order differential equations problem, as seen by an
* integrator is the time derivative dY/dt of a state
* vector Y, both being one dimensional arrays. From the
* integrator point of view, this derivative depends only on the
* current time t and on the state vector
* Y.
*
* For real problems, the derivative depends also on parameters
* that do not belong to the state vector (dynamical model constants
* for example). These constants are completely outside of the scope
* of this interface, the classes that implement it are allowed to
* handle them as they want.
*
* @see FirstOrderFieldIntegrator
*
* @param the type of the field elements
* @since 3.6
*/
public interface FirstOrderFieldDifferentialEquations> {
/** Get the dimension of the problem.
* @return dimension of the problem
*/
int getDimension();
/** Initialize equations at the start of an ODE integration.
*
* This method is called once at the start of the integration. It
* may be used by the equations to initialize some internal data
* if needed.
*
* @param t0 value of the independent time variable at integration start
* @param y0 array containing the value of the state vector at integration start
* @param finalTime target time for the integration
*/
void init(T t0, T[] y0, T finalTime);
/** Get the current time derivative of the state vector.
* @param t current value of the independent time variable
* @param y array containing the current value of the state vector
* @return time derivative of the state vector
*/
T[] computeDerivatives(T t, T[] y);
}