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package org.apache.commons.math3.ode;

import org.apache.commons.math3.exception.DimensionMismatchException;
import org.apache.commons.math3.exception.MaxCountExceededException;



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 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 Also:
FirstOrderIntegrator
FirstOrderConverter
SecondOrderDifferentialEquations
Since:
1.2/** This interface represents a first order differential equations set.
 *
 * <p>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.</p>
 *
 * <p>A first order differential equations problem, as seen by an
 * integrator is the time derivative <code>dY/dt</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> and on the state vector
 * <code>Y</code>.</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 FirstOrderIntegrator
 * @see FirstOrderConverter
 * @see SecondOrderDifferentialEquations
 *
 * @since 1.2
 */

public interface FirstOrderDifferentialEquations {

    
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 – placeholder array where to put the time derivative of the state vector
Throws:
MaxCountExceededException – if the number of functions evaluations is exceeded
DimensionMismatchException – if arrays dimensions do not match equations settings/** 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 placeholder array where to put the time derivative of the state vector
     * @exception MaxCountExceededException if the number of functions evaluations is exceeded
     * @exception DimensionMismatchException if arrays dimensions do not match equations settings
     */
    void computeDerivatives(double t, double[] y, double[] yDot)
        throws MaxCountExceededException, DimensionMismatchException;

}