////////  File: Vector.C  //////////
#include  <iostream.h>
#include  "Vector.h"

Vector::Vector(float a, float b)
{   x = a;  
    y = b;
}

float Vector::inner(Vector a)
{  return(x * a.x + y * a.y);   }

void Vector::display()
{     cout << "(" << x << ",  "
           << y << ")";
}

Vector Vector::operator-(Vector a)
{ Vector tmp;
     tmp.x = x - a.x;
     tmp.y = y - a.y;
     return(tmp);
}

inline float ABS(float x)
       {  return (x > 0 ? x : -x); }

// test if the host is parallel to a (pointing in the same direction)

int Vector::is_parallel(Vector a)
{   return( nonzero() && a.nonzero() &&
            x*a.x >= 0.0 &&
            y*a.y >= 0.0 &&
	    ABS(x*a.y-y*a.x) < 0.00000001
	  );
}