RungeKuttaSolver.cpp
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	/*
	* RungeKuttaSolver.cpp
	*
	* Created on: Oct 25, 2012
	* Author: rpopescu
	*/

	#include "RungeKuttaSolver.hpp"

	#include <cmath>

	RungeKuttaSolver::RungeKuttaSolver()
	{}

	RungeKuttaSolver::~RungeKuttaSolver()
	{}

	void RungeKuttaSolver::SolveEquation(std::ostream& stream)
	{
	double y_prev = GetInitialValue();
	double y_next;

	double t_prev = GetInitialTime();
	double t_next;

	double h = GetStepSize();
	int n = static_cast<int>(
	std::floor((GetFinalTime() - GetInitialTime()) / h));

	stream << t_prev << " " << y_prev << "\n";

	for (int i = 1; i <= n; ++i) {
	double k1 = h * RightHandSide(y_prev, t_prev);
	double k2 = h * RightHandSide(y_prev + 0.5 * k1, t_prev + 0.5 * h);
	double k3 = h * RightHandSide(y_prev + 0.5 * k2, t_prev + 0.5 * h);
	double k4 = h * RightHandSide(y_prev + k3, t_prev + h);

	y_next = y_prev + 1.0/6.0 * (k1 + 2 * k2 + 2 * k3 + k4);
	t_next = t_prev + h;

	stream << t_next << " " << y_next << "\n";
	y_prev = y_next;
	t_prev = t_next;
	}
	}