public class Vector{
    double[] v;
    double squaredNorm;
    double norm;

    Vector(){
	v=new double[3];
    }

    Vector(double[] vs, int n){
	v=new double[n];
	for (int i=0; i<n; i++){
	    v[i]=vs[i];
	}
    }

    Vector(double[] vs){
	v=new double[3];
	v[0]=vs[0];
	v[1]=vs[1];
	v[2]=vs[2];
	squaredNorm=vs[0]*vs[0]+vs[1]*vs[1]+vs[2]*vs[2];
	norm=Math.sqrt(squaredNorm);
    }

    Vector(Vector vs){
	v=new double[3];
	v[0]=vs.v[0];
	v[1]=vs.v[1];
	v[2]=vs.v[2];
	squaredNorm=vs.squaredNorm;
	norm=vs.norm;
    }
   Vector(Vector vs, int n){
	v=new double[n];
	for (int i=0; i<n; i++){
	    v[i]=vs.v[i];
	}	
        squaredNorm=vs.squaredNorm;
	norm=vs.norm;
    }

    

   public double dotP(Vector ws){
       return v[0]*ws.v[0]+v[1]*ws.v[1]+v[2]*ws.v[2];
   }

   public double dotP(double[] ws){
       return v[0]*ws[0]+v[1]*ws[1]+v[2]*ws[2];
   }

    Vector minus(){
	Vector res= new Vector();
	res.v[0]=-v[0];
	res.v[1]=-v[1];
	res.v[2]=-v[2];
	res.squaredNorm=squaredNorm;
	res.norm=norm;
	return res;
    }
	

    Vector scalMult(double k){
	Vector res=new Vector();
	res.v[0]=k*v[0];
	res.v[1]=k*v[1];
	res.v[2]=k*v[2];
	res.squaredNorm=k*k*squaredNorm;
	res.norm=k*norm;
	return res;
    }

     Vector diff(Vector ws){
	double[] tmp=new double[3];
	tmp[0]=v[0]-ws.v[0];
	tmp[1]=v[1]-ws.v[1];
	tmp[2]=v[2]-ws.v[2];
	Vector res=new Vector(tmp);
	return res;
    }

     Vector diff(double[] ws){
	double[] tmp=new double[3];
	tmp[0]=v[0]-ws[0];
	tmp[1]=v[1]-ws[1];
	tmp[2]=v[2]-ws[2];
	Vector res=new Vector(tmp);
	return res;
    }

  Vector add(Vector ws){
	double[] tmp=new double[3];
	tmp[0]=v[0]+ws.v[0];
	tmp[1]=v[1]+ws.v[1];
	tmp[2]=v[2]+ws.v[2];
	Vector res=new Vector(tmp);
	return res;
    }

  Vector add(double[] ws){
	double[] tmp=new double[3];
	tmp[0]=v[0]+ws[0];
	tmp[1]=v[1]+ws[1];
	tmp[2]=v[2]+ws[2];
	Vector res=new Vector(tmp);
	return res;
    }

	
    void normalize(){
	if (norm!=0){
	    v[0]=v[0]/norm;
	    v[1]=v[1]/norm;
	    v[2]=v[2]/norm;
	    squaredNorm=1;
	    norm=1;
	}
    }
	
}