static double f_E(double E, double r)
{
Func <double, vector, vector> swave = (x, y) => new vector(y[1], -2 * (1 / x + E) * y[0]);
double rmin = 1e-3;
vector frmin = new vector(rmin * (1 - rmin), 1 - 2 * rmin);
AdaptOdeSolver solver = new AdaptOdeSolver(swave, rmin, frmin, r, 1e-3, 1e-3, 1e-3);
return(solver.yData[solver.yData.Count - 1][0]);
}
static void Main()
{
// This main solves the ODE from 0 to pi
// u'' = -u, u'(0) = 0, u(0) = 1, which has the solution
// cos(x)
Func <double, vector, vector> dydx = (x, y) => new vector(y[1], -y[0]);
vector yt = new vector(1.0, 0.0);
double a = 0, b = 2 * PI, h = 1 / 20.0;
double absAcc = 1 / 100.0;
double relAcc = 1 / 100.0;
AdaptOdeSolver solver = new AdaptOdeSolver(dydx, a, yt, b, h, absAcc, relAcc);
for (int i = 0; i < solver.yData.Count; i++)
{
WriteLine($"{solver.xData[i]} {solver.yData[i][0]} {solver.yData[i][1]}");
}
}
static void Main()
{
Func <double, vector, vector> f = delegate(double x, vector y){
vector r1 = new vector(y[0], y[1]);
vector r2 = new vector(y[2], y[3]);
vector r3 = new vector(y[4], y[5]);
double r12 = Pow((r2 - r1).norm(), 3);
double r13 = Pow((r3 - r1).norm(), 3);
double r23 = Pow((r3 - r2).norm(), 3);
vector ddr1 = (r2 - r1) / r12 + (r3 - r1) / r13;
vector ddr2 = (r1 - r2) / r12 + (r3 - r2) / r23;
vector ddr3 = (r1 - r3) / r13 + (r2 - r3) / r23;
double[] r = new double[] { y[6], y[7], y[8], y[9], y[10], y[11],
ddr1[0], ddr1[1], ddr2[0], ddr2[1], ddr3[0], ddr3[1] };
return(new vector(r));
};
// Initial condition
double x1 = -1.0024277970, x2 = 0.0041695061, v1 = 0.3489048974, v2 = 0.5306305100;
vector y0 = new vector(new double[] { x1, x2, -x1, -x2, 0, 0, v1, v2, v1, v2, -2 * v1, -2 * v2 });
// Start and end points, accuracy and step size
double a = 0, b = 10, absAcc = 1e-3, relAcc = 1e-3, h = 1e-3;
// Solve system
AdaptOdeSolver Solver = new AdaptOdeSolver(f, a, y0, b, h, absAcc, relAcc);
// Write data for plotting
for (int i = 0; i < Solver.yData.Count; i++)
{
Write($"{Solver.xData[i]} ");
for (int j = 0; j < 6; j++)
{
Write($"{Solver.yData[i][j]} ");
}
Write("\n");
}
}