pse problem 4.9.cpp

#include "stdafx.h"

#include "..\..\include\symbolicc++.h"

Symbolic Pi = "Pi";

Symbolic g = "g";

Symbolic Radians(Symbolic n) { return n * Pi / 180; }

Symbolic Degrees(Symbolic n) { return 180 * n / Pi; }

class Point
{
public:
	
	Symbolic x;
	Symbolic y;
	
	Point() { x = "NOTSET" ; y = "NOTSET"; }

	Point(Symbolic x_val, Symbolic y_val)
	{
		x = x_val;
		y = y_val;
	}

	void Print()
	{
		cout << "Point(" << x << ", " << y << ")";
	}

	static Point FromAngle(Symbolic angle, Symbolic mag)
	{ return Point(cos(angle) * mag, sin(angle) * mag); }

	Point operator+(Point p) { return Point(x + p.x, y + p.y); }

	Point operator*(Symbolic sym) { return Point(x * sym, y * sym); }

	Point operator/(Symbolic sym) { return Point(x / sym, y / sym); }

	Symbolic Norm() { return sqrt(x*x + y*y); }

	double ToAngle() { return atan2(y, x); }
};

void Unset(Symbolic &sym) { sym = "NOTSET"; }

bool IsSet(Symbolic sym) 
{ 
	if (sym == "NOTSET")
		return false;
	else
		return true;
}

bool HasVal(Symbolic sym) 
{ 
	if (sym == "NOTSET")
		return false;
	else
		return true;
}

class Obj
{
public:
	Point position, velocity, acceleration;

	Symbolic time;

	void Print()
	{
		// cout << "Obj:" << endl;
		cout << "time:           " << time << endl;
		cout << "position.x:     " << position.x << endl;
		cout << "position.y:     " << position.y << endl;
		cout << "velocity.x:     " << velocity.x << endl;
		cout << "velocity.y:     " << velocity.y << endl;
		cout << "acceleration.x: " << acceleration.x << endl;
		cout << "acceleration.y: " << acceleration.y << endl;
	}

	Obj AtTime(Symbolic t)
	{
		Obj obj;

		obj.time = t;

		auto dt = t - time;

		obj.acceleration = acceleration;
		obj.velocity = velocity + acceleration * dt;
		obj.position = position + velocity * dt + acceleration * dt * dt / 2;

		return obj;
	}
};

Symbolic CalcTime(Obj& a, Obj& b, int flag=0)
{
	if (HasVal(b.velocity.x) &&
		HasVal(a.velocity.x) &&
		HasVal(a.acceleration.x) &&
		a.acceleration.x != 0.0 &&
		a.acceleration.x != 0)
		return (b.velocity.x - a.velocity.x) / a.acceleration.x;

	if (HasVal(b.velocity.y) &&
		HasVal(a.velocity.y) &&
		HasVal(a.acceleration.y) &&
		a.acceleration.y != 0.0 &&
		a.acceleration.y != 0)
		return (b.velocity.y - a.velocity.y) / a.acceleration.y;

	if (HasVal(a.position.x) &&
		HasVal(b.position.x) &&
		HasVal(a.velocity.x) &&
		a.velocity.x != 0 &&
		a.velocity.x != 0.0)
		return (b.position.x - a.position.x) / a.velocity.x;

	if (HasVal(b.position.x) &&
		HasVal(a.position.x) &&
		HasVal(a.velocity.x) &&
		HasVal(a.acceleration.x) &&
		a.acceleration.x != 0 &&
		a.acceleration.x != 0.0)
	{
		if (flag == 0)
			return
				(-a.velocity.x + sqrt(pow(a.velocity.x, Symbolic(2)) - 2 * a.acceleration.x * (a.position.x - b.position.x)))
				/
				a.acceleration.x;
		else
			return
				(-a.velocity.x - sqrt(pow(a.velocity.x, Symbolic(2)) - 2 * a.acceleration.x * (a.position.x - b.position.x)))
				/
				a.acceleration.x;
	}

	if (HasVal(a.position.y) &&
		HasVal(b.position.y) &&
		HasVal(a.velocity.y) &&
		HasVal(a.acceleration.y) &&
		a.acceleration.y != 0 &&
		a.acceleration.y != 0.0)
	{
		if (flag == 0)
			return
				(-a.velocity.y + sqrt(pow(a.velocity.y, Symbolic(2)) - 2 * a.acceleration.y * (a.position.y - b.position.y)))
				/
				a.acceleration.y;
		else
			return
				(-a.velocity.y - sqrt(pow(a.velocity.y, Symbolic(2)) - 2 * a.acceleration.y * (a.position.y - b.position.y)))
				/
				a.acceleration.y;
	}

	throw "exception";
}

Symbolic CalcInitialVelocityX(Obj& a, Obj& b)
{
	if (HasVal(a.position.x) &&
		HasVal(a.position.y) &&
		HasVal(a.time) &&
		HasVal(b.time) &&
		HasVal(a.acceleration.x))
	{
		auto dt = b.time - a.time;

		return (b.position.x - a.position.x - a.acceleration.x * dt^2 / 2) / dt;
	}

	throw "exception";
}

auto _g = Point(0, -g);

int _tmain(int argc, _TCHAR* argv[])
{	
	// In a local bar, a customer slides an empty beer mug
	// down the counter for a refill. The bartender is 
	// momentarily distracted and does not see the mug, which slides
	// off the counter and strikes the floor 1.40 m from the
	// base of the counter. If the height of the counter is 
	// 0.860 m, (a) with what velocity did the mug leave the
	// counter and (b) what was the direction of the mug’s 
	// velocity just before it hit the floor?

	{
		Obj objA;
		Obj objB;
		
		objA.time = 0;

		objA.position.x = 0;
		objA.position.y = 0.86;

		objA.velocity.y = 0;

		_g = Point(0, -9.8);

		objA.acceleration = _g;


		objB.position.x = 1.4;
		objB.position.y = 0;
		
		objB.acceleration = _g;

		objB.time = CalcTime(objA, objB, 1);

		objA.velocity.x = CalcInitialVelocityX(objA, objB);

		cout << "with what velocity did the mug leave the counter" << endl;
		objA.velocity.Print();
		cout << endl;

		objB = objA.AtTime(objB.time);

		cout << "what was the direction of the mug's velocity just before it hit the floor?" << endl;
		cout << Degrees(objB.velocity.ToAngle())[Pi == 3.14159] << endl;
	}
	system("pause");
	return 0;
}