static void Main0(string[] args)
{
// Constants
const double GM = 1.0; // Gravitational coefficient
const double e = 0.9; // Eccentricity
const double t_end = 20.0; // End time
Geo.Algorithm.Vector Kep = new Geo.Algorithm.Vector(1.0, e, 0.0, 0.0, 0.0, 0.0); // (a,e,i,Omega,omega,M)
Geo.Algorithm.Vector y_ref = Kepler.State(GM, Kep, t_end); // Reference solution
// Variables
double t; // Time
double relerr, abserr; // Accuracy requirements
Geo.Algorithm.Vector y = new Geo.Algorithm.Vector(6); // State vector
AuxDataRecord Aux = new AuxDataRecord(); // Auxiliary satData
DeIntegrator Orbit = new DeIntegrator(f_Kep6D_, 6, Aux); // Object for integrating the
// differential equation
// defined by f_Kep6D_
// Header
var info = "Exercise 4-3: Step size control of DE multistep method" + "\r\n";
info += " Step t h r " + "\r\n";
Console.WriteLine(info);
// Initial values
t = 0.0;
y = new Geo.Algorithm.Vector(1.0 - e, 0.0, 0.0, 0.0, Math.Sqrt((1 + e) / (1 - e)), 0.0);
Aux.n_step = 0;
Aux.t = 0;
relerr = 0.0;
abserr = 1.0e-8;
// Integration from t=t to t=t_end
Orbit.Init(t, relerr, abserr);
Orbit.Integ(t_end, y);
Console.ReadKey();
}
//------------------------------------------------------------------------------
//
// f_Kep6D_
//
// Purpose:
//
// Computes the derivative of the state vector for the normalized (GM=1)
// Kepler's problem in three dimensions
//
// Note:
//
// pAux is expected to point to a variable of type AuxDataRecord, which is
// used to communicate with the other program sections and to hold satData
// between subsequent calls of this function
//
//------------------------------------------------------------------------------
static Geo.Algorithm.Vector f_Kep6D_(double t, Geo.Algorithm.Vector y, Object pAux)
{
// State vector derivative
Geo.Algorithm.Vector r = y.Slice(0, 2);
Geo.Algorithm.Vector v = y.Slice(3, 5);
Geo.Algorithm.Vector yp = v.Stack(-r / (Math.Pow(r.Norm(), 3)));
// Pointer to auxiliary satData record
AuxDataRecord p = (AuxDataRecord)pAux;// static_cast<AuxDataRecord*>(pAux);
// Write current time, step aboutSize and radius; store time for next step
if (t - p.t > 1.0e-10)
{
p.n_step++;
var info = String.Format("{0, 5:D}{1,12:F6}{2,12:F6}{3,12:F3}", p.n_step, t, t - p.t, r.Norm());
Console.WriteLine(info);
p.t = t;
}
;
pAux = p;
return(yp);
}
