public double dist(Math_Vector other){
  double distX=this.x - other.x;
  double distY=this.y - other.y;
  return Math.sqrt(distX * distX + distY * distY);
}

public double dist ( Math_Vector other ) { double distX = this . x - other . x ; double distY = this . y - other . y ; return Math . sqrt ( distX * distX + distY * distY ) ; }
calculate each vector ' s distance
