Example: Adams-Gear ordinary differential equation solver

using System;
using Imsl.Math;

public class OdeAdamsGearEx1
{
    private class MyFunction : OdeAdamsGear.IFunction
    {
        public MyFunction(double k1, double k2, double k3)
        {        
            this.k1 = k1;
            this.k2 = k2;
            this.k3 = k3;
        }

        private double k1;
        private double k2;
        private double k3;
        public virtual double[] F(double t, double[] y)
        {
            double[] yprime = new double[y.Length];
            yprime[0] = - y[0] - y[0] * y[1] + k1 * y[1];
            yprime[1] = (- k2) * y[1] + k3 * (1.0 - y[1]) * y[0];
            return yprime;
        }
    }
    
    public static void  Main(String[] args)
    {
        double k1 = 294.0;
        double k2 = 3.0;
        double k3 = 0.01020408;
        
        OdeAdamsGear.IFunction f = new MyFunction(k1, k2, k3);
        
        double t = 0.0;
        double tend = 240.0;
        double[] y = {1.0, 0.0};
        OdeAdamsGear q = new OdeAdamsGear(f);
        q.NormMethod = OdeAdamsGear.ErrorNormOptions.Abs;
        q.SolveMethod =
            OdeAdamsGear.SolveOption.ChordComputedJacobian;
        q.Tolerance = 1e-3;
        q.Solve(t, tend, y);
        
        // Print Results
        
        Console.Out.WriteLine("Result = {{{0,5:0.####}, {1,5:0.####}}}",
            y[0], y[1]);
    }
}

Output

Result = {0.3924, 0.0013}