using System;

using System.Windows.Forms;

using DotNumerics.ODE;

namespace DotNumericsDemo.DifferentialEquations

{

    public partial class GearsBDF : Form

    {

        private OdeGearsBDF odeBDF = new OdeGearsBDF();

        private double _mu = 500d;

        private void Solve()

        {

            OdeFunction fun = new OdeFunction(ODEs);

            double[] y0 = new double[2];

            y0[0] = 2;

            y0[1] = 0;

            this.odeBDF.InitializeODEs(fun, 2, 0, y0);

            double[] y;

            double t;

            double[,] sol = new double[3001, 2];

            for (int i = 0; i <= 3000; i++)

            {

                t = i;

                y = odeBDF.Solve(t);

                sol[i, 0] = t;

                sol[i, 1] = y[0];

            }

        }

        //The van der Pol equation:

        //            y''-mu*(1-y^2)*y'+y=0

        //If y0=y and y1=y' then:

        //            y0' = y1,                               y0(0)= 2

        //            y1' = mu * (1 - y0 ^2) * y1 - y0        y1(0)=0

        double[] yprime = new double[2];

        private double[] ODEs(double t, double[] y)

        {

            yprime[0] = y[1];

            yprime[1] = this._mu * (1 - y[0] * y[0]) * y[1] - y[0];

            return this.yprime;

        }

    }

}