i need help about this code please help!!

[snvngrc1]

#include <iostream>
#include<math.h>

using namespace std;


class Vect3D
{
	friend Vect3D& operator*(double, const Vect3D&) ;
	friend ostream& operator<<(ostream&, const Vect3D&);
public:
	Vect3D();
	Vect3D(double, double, double);
	const double& operator[](int i) const;
	double& operator[](int i);
	Vect3D& operator+(const Vect3D&) const;
	Vect3D& operator+=(const Vect3D&);
	Vect3D& operator*=(double);
	Vect3D& operator*(double) const;
	bool operator==(const Vect3D&) const;
	static int solveQuadratic(Vect3D &, double&, double&);
private:
	double v[3];
};

class Particle {
public:
	Particle(double mass, Vect3D &location = Vect3D(0,0,0), Vect3D &velocity = Vect3D(0,0,0));
	void applyForce(Vect3D&);
	// inline void applyGravity();  w/o implementation would be OK too  
	inline void applyGravity() {
		Vect3D force = Vect3D(0,0,0-g);
		force *= mass;
		applyForce(force); 
	}; 
	void tick(double t);
	Particle& operator+= (double);
	Particle& operator-= (double);
	Particle& operator+= (const Particle &);
	friend ostream& operator<<(ostream&, Particle const&);
	friend istream& operator>>(istream&, Particle&);
	friend double collisionTime(Particle &, Particle&);
private:
	static const double g=9.81;
	static void intersectSolutions(double &t1, double &t2, double tt1, double tt2);
	double mass;
	Vect3D location;
	Vect3D velocity;
	Vect3D acceleration;
};





Particle& Particle::operator+= (double mass){
	double prevMass = this->mass;
	this->mass += mass;
	this->acceleration *= (prevMass / this->mass);
	return *this;
}


Particle& Particle::operator-= (double mass){
	double prevMass = this->mass;
	this->mass -= mass;
	this->acceleration *= (prevMass / this->mass);
	return *this;
}


Particle& Particle::operator+= (const Particle &other) {
	if (!(location == other.location)) {
		cerr << "Particles not in same location" << endl;
		exit(1);
	}
	double oldMass = mass;
	double newMass = mass + other.mass;
	velocity = (1/newMass) * (mass * velocity + other.mass * other.velocity);
	mass = newMass;
	applyForce(oldMass * acceleration + other.mass * other.acceleration);
	return *this;
}

ostream& operator<<(ostream &out, const Particle &p) {
	out << "Mass : " << p.mass << endl;
	out << "Location     : " << p.location << endl;
	out << "Velocity     : " << p.velocity << endl; 
	out << "Acceleration : " << p.acceleration << endl;
	return out;
}


istream& operator>>( istream &in, Particle& p ){
      
         return in;
}

double collisionTime(Particle &p1, Particle&p2) {
	Vect3D location = p1.location + -1 * p2.location;
	Vect3D velocity = p1.velocity + -1 * p2.velocity;
	Vect3D acceleration = p1.acceleration + -1 * p2.acceleration;
	Vect3D quadratic[3];
	for (int i=0;i<3;i++) {
		quadratic[i][0] = acceleration[i]/2;
		quadratic[i][1] = velocity[i];
		quadratic[i][2] = location[i];
	}
	double t1, t2;
	double tempT1, tempT2;
	if (!Vect3D::solveQuadratic(quadratic[0], t1, t2)) return -1;
	if (!Vect3D::solveQuadratic(quadratic[1], tempT1, tempT2)) return -1;
	Particle::intersectSolutions(t1,t2,tempT1, tempT2);
	if (!Vect3D::solveQuadratic(quadratic[2], tempT1, tempT2)) return -1;
	Particle::intersectSolutions(t1,t2,tempT1, tempT2);
	return t1 != -1 ? t1 : t2;
}

void Particle::intersectSolutions(double &t1, double &t2, double tt1, double tt2) {
	if (tt1 == t1 && tt2 == t2) {              // both solutions OK, do nothing preserve solution
	} else if (tt1 == t1 || tt2 == t1) {       // t1 is a good solution, preserve it, destroy t2
		t2 = -1;
	} else if (tt1 == t2 || tt2 == t2) {       // t2 is a good solution, preserve it, destroy t1
		t1 = -1;
	} else {
		t1 = t2 = -1;                          // No solution is OK
	}
}

/*********************************************************************
 * End of answer to Question 2
 ********************************************************************/
Particle::Particle(double mass, Vect3D &location, Vect3D &velocity) {
	
}

void Particle::applyForce(Vect3D&v) {    
	return;
}

void Particle::tick(double seconds) {
	return;
}



Vect3D::Vect3D() {
	v[1]=v[2]=v[3]=0;
}

Vect3D::Vect3D(double d1, double d2, double d3) {
	v[1]=d1; v[1]=d2;	v[1]=d3;
}

const double& Vect3D::operator[](int i) const {
	return v[i];
}

double& Vect3D::operator[](int i) {
	return v[i];
}

Vect3D& Vect3D::operator+(const Vect3D &other) const {
	Vect3D* ret = new Vect3D(v[1]+other.v[1],v[2]+other.v[2],v[3]+other.v[3]);
	return *ret;
}

Vect3D& Vect3D::operator+=(const Vect3D &other) { 
	for (int i=0; i<3; i++) {
		v[i]+=other.v[i];
	} 
	return *this; 
}
Vect3D& Vect3D::operator*=(double d) {
	for (int i=0; i<3; i++) {
		v[i]*=d;
	} 
	return *this; 	
}
Vect3D& Vect3D::operator*(double d) const {
	Vect3D *ret = new Vect3D(v[1]*d,v[2]*d,v[3]*d);
	return *ret;
}

bool Vect3D::operator==(const Vect3D &other) const {
	for(int i=0; i<3; i++) {
		if (other.v[i] != v[i]) return false;
	}
	return true;
}

/**************************************************
 *                 static methods
 * ***********************************************/
int Vect3D::solveQuadratic(Vect3D&v, double&s1, double&s2) {
	double discriminant = v.v[1]*v.v[1] - 4 * v.v[0] * v.v[2];
	if (discriminant < 0) return 0;
	else if (discriminant == 0) {
		s1 = s2 = v.v[1] / (-2 * v.v[0]);
		return 1;
	} else {
		s1 =  (-1 * v.v[1] + sqrt(discriminant)) / (2 * v.v[0]);		
		s2 =  (-1 * v.v[1] - sqrt(discriminant)) / (2 * v.v[0]);
		return 2;
	}
}

/**************************************************
 *                 friends
 * ***********************************************/
Vect3D& operator*(double d, const Vect3D&v) {
	return v*d;
}

ostream& operator<<(ostream &out, const Vect3D &v) {
	out << '(' << v.v[1] << ',' << v.v[2] << ',' << v.v[3] << ')';
	return out;
}



static double const PI = 3.14;



int main(int argc, char *argv[]) {
	double m, R;
	
	// Get input and initialize particle
	cout << "Enter mass and then radius: " << endl;
	cin >> m >> R;
	double omega = PI/180;
	Vect3D location = Vect3D(0,R,0);
	Vect3D velocity = Vect3D(omega * R, 0, 0);
	Particle p = Particle(m, location, velocity);
	
	// The absolute value of the force remains the same, however the angle changes
	// therefore we calculate it only once
	double absoluteForce = m * omega * omega * R; 
	// At each second recalculate the force and apply the momentary force
	for (int i=0; i < 360; i++) {
		double angle = i * omega;
		Vect3D force;
		force[0]= absoluteForce * sin(angle);
		force[1]= 0- absoluteForce * cos(angle);
		p.applyForce(force);
		p.tick(1);
		cout << p;
	}
	system("pause");
	return 0;
}

[snvngrc1]

i could not implement the empty functions. Can somebody help me?

[Ancient Dragon]

You won't get much help by posting all that unformatted code. Learn to use code tags. You still have time -- go back and edit that post to add the tags.

[snvngrc1]

i could not understand what's wrong about this tag

[Ancient Dragon]

Go back to your original post, hit the "EDIT THIS POST" button, then put [code] before the first line and [/code] after the last line. You will see the difference.

[snvngrc1]

i think it is ok

[Ancient Dragon]

Yes :)

[mrnutty]

to put code tags, do this :

code */code , except delete * and leave no space in between.

[Ancient Dragon]

Since we don't have the assignment I can only guess (give it my best shot).

Particle::Particle(double mass, Vect3D &location, Vect3D &velocity) {
	
}

All you have to do here is initialize each of the class variables with the parameters.

void Particle::applyForce(Vect3D&v) {    
	return;
}

void Particle::tick(double seconds) {
	return;
}

I don't have any idea what those two functions are supposed to do.

[Ancient Dragon]

to put code tags, do this :

(code) (/code) , except delete and leave no space in between.

You don't read very well, do you.:'(

[snvngrc1]

i think you can understand what the assigment about. But actually i din not understand what tick mean is :D

[Ancient Dragon]

>>i think you can understand what the assigment about.
That is an invalid assumption. How can I possibly know what the assignment is about if I have not attended your classes or read the assignment paper ???

>>But actually i din not understand what tick mean is
Neither does anyone else. Could the the tick of a clock, or a nasty creature you pick up on wooded areas (wood ticks).

[snvngrc1]

if i have the assigment paper i would post it :( but this is a particle has mass , velocity, acceleration and location variables.