ODE.java
/**
A generic interface to an ODE problem.
*/
public interface ODE
{
/**
Return state vector for the system of equations.
Time should be the first element of the array.
*/
public double[] getState();
/**
Compute and return (in <code>rate</code>) the time derivatives
of the system of equations whose state vector is represented by
<code>state</code>. In general, <code>rate[i]</code> should be
the time derivative of <code>state[i]</code>; <code>rate[0]</code>
should be 1.0 (the time derivative of time!).
*/
public void getRate(double[] state,double[] rate);
}