package com.imsl.test.example.math;

import com.imsl.math.*;

/**
 * <p>
 * Solves an ODE using the Runge-Kutta-Verner method.</p>
 *
 * An ordinary differential equation problem is solved using a solver which
 * implements the Runge-Kutta-Verner method. The solution at time t=10 is
 * printed.
 *
 *
 * @see <a href="OdeRungeKuttaEx1.java"> Code</a>
 * @see <a href ="doc-files/OdeRungeKuttaEx1.out">Output</a>
 *
 */
public class OdeRungeKuttaEx1 {

    public static void main(String args[]) throws com.imsl.IMSLException {
        OdeRungeKutta.Function fcn = new OdeRungeKutta.Function() {
            public void f(double t, double y[], double yprime[]) {
                yprime[0] = 2. * y[0] * (1 - y[1]);
                yprime[1] = -y[1] * (1 - y[0]);
            }
        };

        double y[] = {1, 3};
        OdeRungeKutta q = new OdeRungeKutta(fcn);
        int nsteps = 10;
        for (int k = 0; k < nsteps; k++) {
            q.solve(k, k + 1, y);
        }
        System.out.println("Result = {" + y[0] + ", " + y[1] + "}");
    }
}