f64/d2/vec.go
func (v Vec) Approx(v2 Vec) bool {
	if !f64.Approx(v.X, v2.X) {
		return false
	}
	if !f64.Approx(v.Y, v2.Y) {
		return false
	}
	return true
}
func (v Vec) Approx(v2 Vec) bool {
	if !f64.Approx(v.X, v2.X) {
		return false
	}
	if !f64.Approx(v.Y, v2.Y) {
		return false
	}
	return true
}
// Approx reports wether v2 is approximately equal to v.
//
// Element-wise approximation uses f64.Approx()