// Calculate a trajectory of a projectile
// no air resistance
#include <iostream>
#include <fstream>
#include <iomanip>
#include <cmath>
using namespace std;

int main()
{
    const double pi=3.1415926;
    const double g = 9.81;
    double y0, v0, angle0, x, y, t, dt;
    double y2;

    ofstream out2disk;
    
    y0 = 0.0;
    v0 = 100.0;
    angle0 = 70.0;
    dt = 0.1; 
    
    angle0 = angle0*pi/180.0;
    
    t = 0.0;
    x = 0.0;
    y = y0;
    
    out2disk.open ("table70.dat");          //open the file
    cout.setf(ios::fixed | ios::showpoint);
    cout.precision(5);
    
//    cout                                  // out to the screen 
    out2disk                                // write to the disk
         << setw(12) <<"t" << setw(12) <<"x" << setw(12) << "y" << endl
         << setw(12) << t  << setw(12) << x  << setw(12) <<  y  << endl;  
    while (y >= 0.0)
    {
	    t = t + dt;
	    x =      v0*cos(angle0)*t;
	    y = y0 + v0*sin(angle0)*t - g*t*t/2.0;
//	    y2 = y0 + x*sin(angle0)/cos(angle0) - g*x*x/(2.0*pow(v0*cos(angle0),2));
//        cout
        out2disk 
        << setw(12) << t  << setw(12) << x  << setw(12) <<  y  
        << endl;
    }
    system ("pause");    
    return 0;
}