#include <stdio.h>
#include <math.h>
#include "winbgi2.h"
#define MAXN 10

double spadek(double t, double V);
void spadekotwarty(double t, double y[], double f[]);
void vrk4(double x0, double y0[], double h, int n, void(*fun)(double, double*, double*), double y1[]);

double Cd, S, ro, m, g;

void main()
{
	double V, t, t0, Vpocz, dt, tk, H;
	double x1, y1;
	double y0[2], y[2];

	g = 9.81; S = 11; ro = 1.225; Cd = 0.3; m = 100.;// dane fizyczne

	graphics(800, 600);

	scanf("%lf", &tk);  t0 = .0;
	Vpocz = 0;
	dt = 0.01;
	scanf("%lf", &H);


	scale(0, -H/3, 300, H+100);
	for (int i = 10; i >= 0; i--) line(tk * (i - 0.25) / 10, 0., tk * (i + 0.25) / 10, 0.);
	// warunki poczatkowe
	t = t0;
	y0[0] = H;
	y0[1] = Vpocz;
//calkowanie
	while (y0[0]>=0)
	{
		vrk4(t, y0, dt, 2, spadekotwarty, y);
		t = t + dt;
		y0[0] = y[0];
		y0[1] = y[1];
		printf("t=%lf   V=%lf   h=%lf\n", t, y[1], y[0]);
		setcolor(1.0); circle(t, y[0], 1);	// czerwone - H WYSOKOSC
		setcolor(0.1); circle(t, y[1], 1);	// niebieskie - V PREDKOSC
	}

	wait();
}


double spadek(double t, double V)
{
	double f;
	if (V>0)	f = -g - ro*S*Cd / 2 / m*V*V;
	else f = -g + ro*S*Cd / 2 / m*V*V;
	return f;
}

void spadekotwarty(double t, double y[], double f[])
{
	f[0] = y[1];
	f[1] = -g - ro*S*Cd / (2 * m) * y[1] * fabs(y[1]);

}

void vrk4(double x0, double y0[], double h, int n, void(*fun)(double, double*, double*), double y1[])
{
	//double MAXN;
	int		i;
	double	k1[MAXN], k2[MAXN], k3[MAXN], k4[MAXN];
	double	ytmp[MAXN];

	fun(x0, y0, k1);
	for (i = 0; i<n; ++i)
	{
		k1[i] *= h;
		ytmp[i] = y0[i] + k1[i] / 2.0;
	}

	fun(x0 + h / 2.0, ytmp, k2);
	for (i = 0; i<n; ++i)
	{
		k2[i] *= h;
		ytmp[i] = y0[i] + k2[i] / 2.0;
	}

	fun(x0 + h / 2.0, ytmp, k3);
	for (i = 0; i<n; ++i)
	{
		k3[i] *= h;
		ytmp[i] = y0[i] + k3[i];
	}

	fun(x0 + h, ytmp, k4);
	for (i = 0; i<n; ++i)
		k4[i] *= h;

	for (i = 0; i<n; ++i)
		y1[i] = y0[i] + (k1[i] + 2.*k2[i] + 2.*k3[i] + k4[i]) / 6.;

}