Since quaternion algebra is division ring, then module over quaternion algebra is called vector space. Because quaternion algebra is non-commutative, we distinguish left and right vector spaces. In left vector space, linear composition of vectors
v
w
av+bw
a
b\inH
v
w
va+wb
If quaternionic vector space has finite dimension
n
Hn
n
H
e1=(1,0,\ldots,0)
\ldots
en=(0,\ldots,0,1)
In left quaternionic vector space
Hn
(p1,\ldots,pn)+(r1,\ldots,rn)=(p1+r1,\ldots,pn+rn)
q(r1,\ldots,rn)=(qr1,\ldots,qrn)
Hn
(p1,\ldots,pn)+(r1,\ldots,rn)=(p1+r1,\ldots,pn+rn)
(r1,\ldots,rn)q=(r1q,\ldots,rnq)