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* Licensed to the Apache Software Foundation (ASF) under one or more
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* 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
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* See the License for the specific language governing permissions and
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*/
package org.apache.commons.math3.ode;
/** This interface represents a second order differential equations set.
* This interface should be implemented by all real second order
* differential equation problems before they can be handled by the
* integrators {@link SecondOrderIntegrator#integrate} method.
*
* A second order differential equations problem, as seen by an
* integrator is the second time derivative d2Y/dt^2 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, on the state vector
* Y and on the first time derivative of the state
* vector.
*
* 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 SecondOrderIntegrator
* @see FirstOrderConverter
* @see FirstOrderDifferentialEquations
* @since 1.2
*/
public interface SecondOrderDifferentialEquations {
/** Get the dimension of the problem.
* @return dimension of the problem
*/
int getDimension();
/** 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
* @param yDot array containing the current value of the first derivative
* of the state vector
* @param yDDot placeholder array where to put the second time derivative
* of the state vector
*/
void computeSecondDerivatives(double t, double[] y, double[] yDot, double[] yDDot);
}