Quaternion
Numbers with four dimensions are called quaternions. You write them as
q = a + bi + cj + dk
and they constst of the real numbers a, b, c, d and the quantities i, j and k. The set of quaternions is denoted by the symbol H (from Hamilton).
Explanation
When multiplying the quantities i, j and k the sequence plays a role.
Quaternions can be used to describe a rotation in three dimensions. A point (b, c, d ) in three dimensions forms the imaginary part bi + cj + dk of a quaternion.
HistoryThe Irisch mathematcian William Rowan Hamilton invented the quaternions in 1843. |