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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 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 Also: Since: 1.2
/** This interface represents a second order differential equations set.
* <p>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.</p>
*
* <p>A second order differential equations problem, as seen by an
* integrator is the second time derivative <code>d2Y/dt^2</code> of a
* state vector <code>Y</code>, both being one dimensional
* arrays. From the integrator point of view, this derivative depends
* only on the current time <code>t</code>, on the state vector
* <code>Y</code> and on the first time derivative of the state
* vector.</p>
*
* <p>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.</p>
*
* @see SecondOrderIntegrator
* @see FirstOrderConverter
* @see FirstOrderDifferentialEquations
* @since 1.2
*/
public interface SecondOrderDifferentialEquations {
Get the dimension of the problem.
Returns: dimension of the problem
/** Get the dimension of the problem.
* @return dimension of the problem
*/
int getDimension();
Get the current time derivative of the state vector.
Params: - t – current value of the independent time variable
- y – array containing the current value of the state vector
- yDot – array containing the current value of the first derivative
of the state vector
- yDDot – placeholder array where to put the second time derivative
of the state vector
/** Get the current time derivative of the state vector.
* @param t current value of the independent <I>time</I> 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);
}