// $AISD_VERSION:RKDemo.java@1.2/home/coei/arc/archive%shell3.ba.best.com$

//COPYRIGHT: Copyright (c) 1997 by Christopher K. Oei, Incorporated.
//COPYRIGHT: 
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//COPYRIGHT: 
//COPYRIGHT: Permission to use, display, and modify this code
//COPYRIGHT: is hereby granted provided that:
//COPYRIGHT: 
//COPYRIGHT: 1) this notice is included in its entirety
//COPYRIGHT: 2) we are notified of the usage

// RKDemo is a class that demonstrates the use of the RKInt class
// by integrating an ODE of the form
//
// dx[0]/dt = -x[1] - 0.05 x[0]
// dx[1]/dt = x[0]
//


import RKInt;
import NumDemo;

public class RKDemo extends RKInt
{
     static double Ideriv=0;	

public RKDemo(double i_t,double[] i_x,double i_dt)
    {
	super(i_t,i_x,i_dt);
    }

protected double[] derivative(double i_t,double[] i_x)
    {
	double q = NumDemo.qvalue;  
	double beta1 = NumDemo.betavalue;
	double[] y = new double[3];
        double beta;
 
        beta=beta1*beta1;

        y[0]=i_x[2];
        y[1]=-q*i_x[1] + beta*i_x[2] * ((1.5*i_x[0])/Math.pow((1.00+Math.pow(i_x[0],2.0)),2.5));
	y[2]=-1.0 - ((1.5*i_x[0])/Math.pow(1.00+Math.pow(i_x[0],2.0),2.5)) * i_x[1];

        Ideriv = y[1];

        return y;
    }
}