// polyAdd adds two ringElements or nttElements.
func polyAdd[T ~[n]fieldElement](a, b T) (s T) {
	for i := range s {
		s[i] = fieldAdd(a[i], b[i])
	}
	return s
}

// polySub subtracts two ringElements or nttElements.
func polySub[T ~[n]fieldElement](a, b T) (s T) {
	for i := range s {
		s[i] = fieldSub(a[i], b[i])
	}
	return s
}

// polyByteEncode appends the 384-byte encoding of f to b.
//