code: function vector2AreEqual (x, y, eps) {
    return (isZero(x.x - y.x, eps) &&
      isZero(x.y - y.y, eps));
  }
docs: Test if a vector length is equal to another vector length within a tolerance.
  @function vector2AreEqual
  @memberof Compare
  @param {Vector2} x The first vector.
  @param {Vector2} y The second vector.
  @param {number} eps The numerical tolerance.
  @returns {boolean} True if vector component differences are within the numerical tolerance, false if not.