/* Method calculating point-wise approximation. Implementation of the Runge-Kutta Method.
* Returns an approximation at a point with given index i.
*/
public override double ComputeForPoint(double[] x, double[] y, int i, DifferentialEquation MyDifferentialEquation)
{
// Initialize temporary variables.
double h = GetStep(), K1, K2, K3, K4;
// By default use RK4.
K1 = MyDifferentialEquation.Derivative(x[i], y[i]);
K2 = MyDifferentialEquation.Derivative(x[i] + h / 2, y[i] + h / 2 * K1);
K3 = MyDifferentialEquation.Derivative(x[i] + h / 2, y[i] + h / 2 * K2);
K4 = MyDifferentialEquation.Derivative(x[i] + h, y[i] + h * K3);
return(y[i] + h / 6 * (K1 + 2 * K2 + 2 * K3 + K4));
}
/* Method calculating point-wise approximation. Implementation of the Euler Method. * Returns an approximation at a point with given index i. */ public override double ComputeForPoint(double[] x, double[] y, int i, DifferentialEquation MyDifferentialEquation) => y[i] + (GetStep() * MyDifferentialEquation.Derivative(x[i], y[i]));