Duals
The dual of an object $$\mathbf x$$, denoted by $$\mathbf x^*$$, is given by
- $$\mathbf x^* = \mathbf G \underline{\mathbf x}$$ ,
where $$\mathbf G$$ is the extended metric tensor, and $$\underline{\mathbf x}$$ is the left complement of $$\mathbf x$$.
The following table lists the duals for the geometric objects in the 5D conformal geometric algebra $$\mathcal G_{4,1}$$.
| Type | Definition | Dual |
|---|---|---|
| Flat point | $$\mathbf p = p_x \mathbf e_{15} + p_y \mathbf e_{25} + p_z \mathbf e_{35} + p_w \mathbf e_{45}$$ | $$\mathbf p^* = -p_w \mathbf e_{321} + p_x \mathbf e_{235} + p_y \mathbf e_{315} + p_z \mathbf e_{125}$$ |
| Line | $$\boldsymbol l = l_{vx} \mathbf e_{415} + l_{vy} \mathbf e_{425} + l_{vz} \mathbf e_{435} + l_{mx} \mathbf e_{235} + l_{my} \mathbf e_{315} + l_{mz} \mathbf e_{125}$$ | $$\boldsymbol l^* = -l_{vx} \mathbf e_{23} - l_{vy} \mathbf e_{31} - l_{vz} \mathbf e_{12} - l_{mx} \mathbf e_{15} - l_{my} \mathbf e_{25} - l_{mz} \mathbf e_{35}$$ |
| Plane | $$\mathbf g = g_x \mathbf e_{4235} + g_y \mathbf e_{4315} + g_z \mathbf e_{4125} + g_w \mathbf e_{3215}$$ | $$\mathbf g^* = g_x \mathbf e_1 + g_y \mathbf e_2 + g_z \mathbf e_3 - g_w \mathbf e_5$$ |
| Round point | $$\mathbf a = a_x \mathbf e_1 + a_y \mathbf e_2 + a_z \mathbf e_3 + a_w \mathbf e_4 + a_u \mathbf e_5$$ | $$\mathbf a^* = a_w \mathbf e_{1234} - a_x \mathbf e_{4235} - a_y \mathbf e_{4315} - a_z \mathbf e_{4125} + a_u \mathbf e_{3215}$$ |
| Dipole | $$\mathbf d = d_{vx} \mathbf e_{41} + d_{vy} \mathbf e_{42} + d_{vz} \mathbf e_{43} + d_{mx} \mathbf e_{23} + d_{my} \mathbf e_{31} + d_{mz} \mathbf e_{12} + d_{px} \mathbf e_{15} + d_{py} \mathbf e_{25} + d_{pz} \mathbf e_{35} + d_{pw} \mathbf e_{45}$$ | $$\mathbf d^* = d_{vx} \mathbf e_{423} + d_{vy} \mathbf e_{431} + d_{vz} \mathbf e_{412} - d_{pw} \mathbf e_{321} + d_{mx} \mathbf e_{415} + d_{my} \mathbf e_{425} + d_{mz} \mathbf e_{435} + d_{px} \mathbf e_{235} + d_{py} \mathbf e_{315} + d_{pz} \mathbf e_{125}$$ |
| Circle | $$\mathbf c = c_{gx} \mathbf e_{423} + c_{gy} \mathbf e_{431} + c_{gz} \mathbf e_{412} + c_{gw} \mathbf e_{321} + c_{vx} \mathbf e_{415} + c_{vy} \mathbf e_{425} + c_{vz} \mathbf e_{435} + c_{mx} \mathbf e_{235} + c_{my} \mathbf e_{315} + c_{mz} \mathbf e_{125}$$ | $$\mathbf c^* = -c_{gx} \mathbf e_{41} - c_{gy} \mathbf e_{42} - c_{gz} \mathbf e_{43} - c_{vx} \mathbf e_{23} - c_{vy} \mathbf e_{31} - c_{vz} \mathbf e_{12} - c_{mx} \mathbf e_{15} - c_{my} \mathbf e_{25} - c_{mz} \mathbf e_{35} + c_{gw} \mathbf e_{45}$$ |
| Sphere | $$\mathbf s = s_u \mathbf e_{1234} + s_x \mathbf e_{4235} + s_y \mathbf e_{4315} + s_z \mathbf e_{4125} + s_w \mathbf e_{3215}$$ | $$\mathbf s^* = s_x \mathbf e_1 + s_y \mathbf e_2 + s_z \mathbf e_3 - s_u \mathbf e_4 - s_w \mathbf e_5$$ |