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1
1
+
2 ( e 12
e 31
e 23 +
1 )
=
2 ( 1
1
+
2 )
1
1
1
1
2
1
+
2 e 12
2 e 23
2 e 31 +
=
3
3
2 +
3
6
3
6
3
6
=
e 12
e 23
e 31
which makes
3
2
3
6
3
6
3
6
R
120 ° =
e 12 +
e 23 +
e 31 .
But does it work? Well, let's find out by forming the product
1
2 ( e 2 +
1
12 2 ( 3
e 3 ) R
R 120 °
120 ° =
+
e 12 +
e 32 +
e 13 )
× ( e 2 +
e 3 )( 3
e 12
e 32
e 13 )
1
6 2 ( e 1 +
=
e 2 +
2 e 3 )( 3
e 12
e 32
e 13 )
1
6 2 ( 6 e 1 +
=
6 e 3 )
1
2 ( e 1 +
=
e 3 )
which is correct.
Finally, let's employ the rotor matrix. But remember that its definition of R θ has
a negative bivector term, which means that we have to switch the bivector terms in
R 120 °
or use the bivector terms from R
120 ° :
3
2
3
6
3
6
3
6
R
120 ° =
e 12 +
e 23 +
e 31
where
3
2
3
6
3
6
3
6
s
=
,x
=
,y
=
,z
=−
2 (y 2
z 2 )
1
+
2 (xy
sz)
2 (xz
+
sy)
v 1
v 2
v 3
R 120 ° vR
2 (x 2
z 2 )
120 ° =
2 (xy
+
sz)
1
+
2 (yz
sx)
2 (x 2
y 2 )
2 (xz
sy)
2 (yz
+
sx)
1
+
2 ( 12 +
1
2 ( 12 +
3
1
3
12 +
1
12 )
12 )
2 (
12 )
v 1
v 2
v 3
2 ( 12
3
2 ( 12 +
1
1
3
=
12 )
1
12 )
2 (
12
12 )
1
3
1
3
2 ( 12 +
1
2 (
12
12 )
2 (
12 +
12 )
1
12 )
2
3
2
3
1
3
v 1
v 2
v 3
.
1
3
2
3
2
3
=
2
3
1
3
2
3
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