Is there a notation/function for "converting" (for want of a better word) a complex number or quaternion into a real vector with a dimension of 2 or 4?
E.g. $2 + 3i + 4j + 9k$ would be $(2, 3, 4, 9)$, $2 + 3j$ would be $(2, 0, 3, 0)$, $2 + 3i$ would be $(2, 3)$.