Expansion

The expansion operation is performed by taking the wedge product between an object A and the antidual of another object B with higher grade. The result is an object C that contains A and is orthogonal to B, allowing a projection of A onto B through a simple intersection of B and C.

The flat points, lines, planes, round points, dipoles, circles, and spheres appearing in the following tables are defined as follows:

$$\mathbf p = p_x \mathbf e_{15} + p_y \mathbf e_{25} + p_z \mathbf e_{35} + p_w \mathbf e_{45}$$

$$\boldsymbol l = l_{vx} \mathbf e_{415} + l_{vy} \mathbf e_{425} + l_{vz} \mathbf e_{435} + l_{mx} \mathbf e_{235} + l_{my} \mathbf e_{315} + l_{mz} \mathbf e_{125}$$

$$\mathbf g = g_x \mathbf e_{4235} + g_y \mathbf e_{4315} + g_z \mathbf e_{4125} + g_w \mathbf e_{3215}$$

$$\mathbf a = a_x \mathbf e_1 + a_y \mathbf e_2 + a_z \mathbf e_3 + a_w \mathbf e_4 + a_u \mathbf e_5$$

$$\mathbf d = d_{vx} \mathbf e_{41} + d_{vy} \mathbf e_{42} + d_{vz} \mathbf e_{43} + d_{mx} \mathbf e_{23} + d_{my} \mathbf e_{31} + d_{mz} \mathbf e_{12} + d_{px} \mathbf e_{15} + d_{py} \mathbf e_{25} + d_{pz} \mathbf e_{35} + d_{pw} \mathbf e_{45}$$

$$\mathbf c = c_{gx} \mathbf e_{423} + c_{gy} \mathbf e_{431} + c_{gz} \mathbf e_{412} + c_{gw} \mathbf e_{321} + c_{vx} \mathbf e_{415} + c_{vy} \mathbf e_{425} + c_{vz} \mathbf e_{435} + c_{mx} \mathbf e_{235} + c_{my} \mathbf e_{315} + c_{mz} \mathbf e_{125}$$

$$\mathbf s = s_u \mathbf e_{1234} + s_x \mathbf e_{4235} + s_y \mathbf e_{4315} + s_z \mathbf e_{4125} + s_w \mathbf e_{3215}$$

Formula	Illustration
Dipole containing round point $$\mathbf a$$ and orthogonal to sphere $$\mathbf s$$. $$\begin{split}\mathbf a \wedge \mathbf s^\unicode["segoe ui symbol"]{x2606} =\, &(a_xs_u + a_ws_x)\,\mathbf e_{41} \,&+\, (a_ys_u + a_ws_y)\,\mathbf e_{42} \,&+\, (a_zs_u + a_ws_z)\,\mathbf e_{43} \\ +\, &(a_ys_z - a_zs_y)\,\mathbf e_{23} \,&+\, (a_zs_x - a_xs_z)\,\mathbf e_{31} \,&+\, (a_xs_y - a_ys_x)\,\mathbf e_{12} \\ -\, &(a_xs_w + a_us_x)\,\mathbf e_{15} \,&-\, (a_ys_w + a_us_y)\,\mathbf e_{25} \,&-\, (a_zs_w + a_us_z)\,\mathbf e_{35} + (a_us_u - a_ws_w)\,\mathbf e_{45} \end{split}$$
Dipole containing round point $$\mathbf a$$ and orthogonal to plane $$\mathbf g$$. $$\begin{split}\mathbf a \wedge \mathbf g^\unicode["segoe ui symbol"]{x2606} =\, &a_wg_x \mathbf e_{41} + a_wg_y \mathbf e_{42} + a_wg_z \mathbf e_{43} \\ +\, &(a_yg_z - a_zg_y)\,\mathbf e_{23} + (a_zg_x - a_xg_z)\,\mathbf e_{31} + (a_xg_y - a_yg_x)\,\mathbf e_{12} \\ -\, &(a_xg_w + a_ug_x)\,\mathbf e_{15} - (a_yg_w + a_ug_y)\,\mathbf e_{25} - (a_zg_w + a_ug_z)\,\mathbf e_{35} - a_wg_w \mathbf e_{45} \end{split}$$
Circle containing dipole $$\mathbf d$$ and orthogonal to sphere $$\mathbf s$$. $$\begin{split}\mathbf d \wedge \mathbf s^\unicode["segoe ui symbol"]{x2606} =\, &(d_{vy}s_z - d_{vz}s_y - d_{mx}s_u)\,\mathbf e_{423} \,&+\, (d_{vz}s_x - d_{vx}s_z - d_{my}s_u)\,\mathbf e_{431} \\ +\, &(d_{vx}s_y - d_{vy}s_x - d_{mz}s_u)\,\mathbf e_{412} \,&-\, (d_{mx}s_x + d_{my}s_y + d_{mz}s_z)\,\mathbf e_{321} \\ -\, &(d_{vx}s_w + d_{pw}s_x + d_{px}s_u)\,\mathbf e_{415} \,&+\, (d_{pz}s_y - d_{py}s_z - d_{mx}s_w)\,\mathbf e_{235} \\ -\, &(d_{vy}s_w + d_{pw}s_y + d_{py}s_u)\,\mathbf e_{425} \,&+\, (d_{px}s_z - d_{pz}s_x - d_{my}s_w)\,\mathbf e_{315} \\ -\, &(d_{vz}s_w + d_{pw}s_z + d_{pz}s_u)\,\mathbf e_{435} \,&+\, (d_{py}s_x - d_{px}s_y - d_{mz}s_w)\,\mathbf e_{125} \end{split}$$
Circle containing dipole $$\mathbf d$$ and orthogonal to plane $$\mathbf g$$. $$\begin{split}\mathbf d \wedge \mathbf g^\unicode["segoe ui symbol"]{x2606} =\, &(d_{vy}g_z - d_{vz}g_y)\,\mathbf e_{423} \,&+\, (d_{vz}g_x - d_{vx}g_z)\,\mathbf e_{431} \\ +\, &(d_{vx}g_y - d_{vy}g_x)\,\mathbf e_{412} \,&-\, (d_{mx}g_x + d_{my}g_y + d_{mz}g_z)\,\mathbf e_{321} \\ -\, &(d_{vx}g_w + d_{pw}g_x)\,\mathbf e_{415} \,&+\, (d_{pz}g_y - d_{py}g_z - d_{mx}g_w)\,\mathbf e_{235} \\ -\, &(d_{vy}g_w + d_{pw}g_y)\,\mathbf e_{425} \,&+\, (d_{px}g_z - d_{pz}g_x - d_{my}g_w)\,\mathbf e_{315} \\ -\, &(d_{vz}g_w + d_{pw}g_z)\,\mathbf e_{435} \,&+\, (d_{py}g_x - d_{px}g_y - d_{mz}g_w)\,\mathbf e_{125} \end{split}$$
Line containing flat point $$\mathbf p$$ and orthogonal to sphere $$\mathbf s$$. $$\begin{split}\mathbf p \wedge \mathbf s^\unicode["segoe ui symbol"]{x2606} = -\, &(p_xs_u + p_ws_x)\,\mathbf e_{415} \,&-\, (p_ys_u + p_ws_y)\,\mathbf e_{425} \,&-\, (p_zs_u + p_ws_z)\,\mathbf e_{435} \\ +\, &(p_zs_y - p_ys_z)\,\mathbf e_{235} \,&+\, (p_xs_z - p_zs_x)\,\mathbf e_{315} \,&+\, (p_ys_x - p_xs_y)\,\mathbf e_{125} \end{split}$$
Line containing flat point $$\mathbf p$$ and orthogonal to plane $$\mathbf g$$. $$\begin{split}\mathbf p \wedge \mathbf g^\unicode["segoe ui symbol"]{x2606} = -\, &p_wg_x \mathbf e_{415} - p_wg_y \mathbf e_{425} - p_wg_z \mathbf e_{435} \\ +\, &(p_zg_y - p_yg_z)\,\mathbf e_{235} + (p_xg_z - p_zg_x)\,\mathbf e_{315} + (p_yg_x - p_xg_y)\,\mathbf e_{125} \end{split}$$
Sphere containing circle $$\mathbf c$$ and orthogonal to sphere $$\mathbf s$$. $$\begin{split}\mathbf c \wedge \mathbf s^\unicode["segoe ui symbol"]{x2606} =\, &(c_{gw}s_u - c_{gx}s_x - c_{gy}s_y - c_{gz}s_z)\,\mathbf e_{1234} \\ +\, &(c_{vz}s_y - c_{vy}s_z + c_{mx}s_u - c_{gx}s_w)\,\mathbf e_{4235} \\ +\, &(c_{vx}s_z - c_{vz}s_x + c_{my}s_u - c_{gy}s_w)\,\mathbf e_{4315} \\ +\, &(c_{vy}s_x - c_{vx}s_y + c_{mz}s_u - c_{gz}s_w)\,\mathbf e_{4125} \\ +\, &(c_{mx}s_x + c_{my}s_y + c_{mz}s_z - c_{gw}s_w)\,\mathbf e_{3215} \end{split}$$
Sphere containing circle $$\mathbf c$$ and orthogonal to plane $$\mathbf g$$. $$\begin{split}\mathbf c \wedge \mathbf g^\unicode["segoe ui symbol"]{x2606} = -\, &(c_{gx}g_x + c_{gy}g_y + c_{gz}g_z)\,\mathbf e_{1234} \\ +\, &(c_{vz}g_y - c_{vy}g_z - c_{gx}g_w)\,\mathbf e_{4235} \\ +\, &(c_{vx}g_z - c_{vz}g_x - c_{gy}g_w)\,\mathbf e_{4315} \\ +\, &(c_{vy}g_x - c_{vx}g_y - c_{gz}g_w)\,\mathbf e_{4125} \\ +\, &(c_{mx}g_x + c_{my}g_y + c_{mz}g_z - c_{gw}g_w)\,\mathbf e_{3215} \end{split}$$
Plane containing line $$\boldsymbol l$$ and orthogonal to sphere $$\mathbf s$$. $$\begin{split}\boldsymbol l \wedge \mathbf s^\unicode["segoe ui symbol"]{x2606} =\, &(l_{vz}s_y - l_{vy}s_z + l_{mx}s_u)\,\mathbf e_{4235} + (l_{vx}s_z - l_{vz}s_x + l_{my}s_u)\,\mathbf e_{4315} \\ +\, &(l_{vy}s_x - l_{vx}s_y + l_{mz}s_u)\,\mathbf e_{4125} + (l_{mx}s_x + l_{my}s_y + l_{mz}s_z)\,\mathbf e_{3215} \end{split}$$
Plane containing line $$\boldsymbol l$$ and orthogonal to plane $$\mathbf g$$. $$\begin{split}\boldsymbol l \wedge \mathbf g^\unicode["segoe ui symbol"]{x2606} =\, &(l_{vz}g_y - l_{vy}g_z)\,\mathbf e_{4235} + (l_{vx}g_z - l_{vz}g_x)\,\mathbf e_{4315} \\ +\, &(l_{vy}g_x - l_{vx}g_y)\,\mathbf e_{4125} + (l_{mx}g_x + l_{my}g_y + l_{mz}g_z)\,\mathbf e_{3215} \end{split}$$
Circle containing round point $$\mathbf a$$ and orthogonal to circle $$\mathbf c$$. $$\begin{split}\mathbf a \wedge \mathbf c^\unicode["segoe ui symbol"]{x2606} =\, &(a_yc_{gz} - a_zc_{gy} - a_wc_{vx})\,\mathbf e_{423} \,&+\, (a_zc_{gx} - a_xc_{gz} - a_wc_{vy})\,\mathbf e_{431} \\ +\, &(a_xc_{gy} - a_yc_{gx} - a_wc_{vz})\,\mathbf e_{412} \,&+\, (a_xc_{vx} + a_yc_{vy} + a_zc_{vz})\,\mathbf e_{321} \\ -\, &(a_wc_{mx} + a_xc_{gw} + a_uc_{gx})\,\mathbf e_{415} \,&+\, (a_zc_{my} - a_yc_{mz} - a_uc_{vx})\,\mathbf e_{235} \\ -\, &(a_wc_{my} + a_yc_{gw} + a_uc_{gy})\,\mathbf e_{425} \,&+\, (a_xc_{mz} - a_zc_{mx} - a_uc_{vy})\,\mathbf e_{315} \\ -\, &(a_wc_{mz} + a_zc_{gw} + a_uc_{gz})\,\mathbf e_{435} \,&+\, (a_yc_{mx} - a_xc_{my} - a_uc_{vz})\,\mathbf e_{125} \end{split}$$
Circle containing round point $$\mathbf a$$ and orthogonal to line $$\boldsymbol l$$. $$\begin{split}\mathbf a \wedge \boldsymbol l^\unicode["segoe ui symbol"]{x2606} = -\, &a_wl_{vx} \mathbf e_{423} - a_wl_{vy} \mathbf e_{431} - a_wl_{vz} \mathbf e_{412}\\ +\, &(a_xl_{vx} + a_yl_{vy} + a_zl_{vz})\,\mathbf e_{321} \\ -\, &a_wl_{mx} \mathbf e_{415} + (a_zl_{my} - a_yl_{mz} - a_ul_{vx})\,\mathbf e_{235} \\ -\, &a_wl_{my} \mathbf e_{425} + (a_xl_{mz} - a_zl_{mx} - a_ul_{vy})\,\mathbf e_{315} \\ -\, &a_wl_{mz} \mathbf e_{435} + (a_yl_{mx} - a_xl_{my} - a_ul_{vz})\,\mathbf e_{125} \end{split}$$
Plane containing flat point $$\mathbf p$$ and orthogonal to circle $$\mathbf c$$. $$\begin{split}\mathbf p \wedge \mathbf c^\unicode["segoe ui symbol"]{x2606} =\, &(p_yc_{gz} - p_zc_{gy} - p_wc_{vx})\,\mathbf e_{4235} \,&+\, (p_zc_{gx} - p_xc_{gz} - p_wc_{vy})\,\mathbf e_{4315} \\ +\, &(p_xc_{gy} - p_yc_{gx} - p_wc_{vz})\,\mathbf e_{4125} \,&+\, (p_xc_{vx} + p_yc_{vy} + p_zc_{vz})\,\mathbf e_{3215} \end{split}$$
Plane containing flat point $$\mathbf p$$ and orthogonal to line $$\boldsymbol l$$. $$\begin{split}\mathbf p \wedge \boldsymbol l^\unicode["segoe ui symbol"]{x2606} = -\, &p_wl_{vx} \mathbf e_{4235} - p_wl_{vy} \mathbf e_{4315} - p_wl_{vz} \mathbf e_{4125} \\ +\, &(p_xl_{vx} + p_yl_{vy} + p_zl_{vz})\,\mathbf e_{3215} \end{split}$$
Sphere containing dipole $$\mathbf d$$ orthogonal to circle $$\mathbf c$$. $$\begin{split}\mathbf d \wedge \mathbf c^\unicode["segoe ui symbol"]{x2606} =\, &(d_{vx}c_{vx} + d_{vy}c_{vy} + d_{vz}c_{vz} + d_{mx}c_{gx} + d_{my}c_{gy} + d_{mz}c_{gz})\,\mathbf e_{1234} \\ +\, &(d_{vz}c_{my} - d_{vy}c_{mz} - d_{pw}c_{vx} + d_{py}c_{gz} - d_{pz}c_{gy} + d_{mx}c_{gw})\,\mathbf e_{4235} \\ +\, &(d_{vx}c_{mz} - d_{vz}c_{mx} - d_{pw}c_{vy} + d_{pz}c_{gx} - d_{px}c_{gz} + d_{my}c_{gw})\,\mathbf e_{4315} \\ +\, &(d_{vy}c_{mx} - d_{vx}c_{my} - d_{pw}c_{vz} + d_{px}c_{gy} - d_{py}c_{gx} + d_{mz}c_{gw})\,\mathbf e_{4125} \\ +\, &(d_{px}c_{vx} + d_{py}c_{vy} + d_{pz}c_{vz} + d_{mx}c_{mx} + d_{my}c_{my} + d_{mz}c_{mz})\,\mathbf e_{3215} \end{split}$$
Sphere containing dipole $$\mathbf d$$ and orthogonal to line $$\boldsymbol l$$. $$\begin{split}\mathbf d \wedge \boldsymbol l^\unicode["segoe ui symbol"]{x2606} =\, &(d_{vx}l_{vx} + d_{vy}l_{vy} + d_{vz}l_{vz})\,\mathbf e_{1234} \\ +\, &(d_{vz}l_{my} - d_{vy}l_{mz} - d_{pw}l_{vx})\,\mathbf e_{4235} \\ +\, &(d_{vx}l_{mz} - d_{vz}l_{mx} - d_{pw}l_{vy})\,\mathbf e_{4315} \\ +\, &(d_{vy}l_{mx} - d_{vx}l_{my} - d_{pw}l_{vz})\,\mathbf e_{4125} \\ +\, &(d_{px}l_{vx} + d_{py}l_{vy} + d_{pzl_{vz}} + d_{mx}l_{mx} + d_{my}l_{my} + d_{mz}l_{mz})\,\mathbf e_{3215} \end{split}$$
Sphere containing round point $$\mathbf a$$ and orthogonal to dipole $$\mathbf d$$. $$\begin{split}\mathbf a \wedge \mathbf d^\unicode["segoe ui symbol"]{x2606} =\, &(a_xd_{vx} + a_yd_{vy} + a_zd_{vz} - a_wd_{pw})\,\mathbf e_{1234} \\ +\, &(a_zd_{my} - a_yd_{mz} + a_wd_{px} - a_ud_{vx})\,\mathbf e_{4235} \\ +\, &(a_xd_{mz} - a_zd_{mx} + a_wd_{py} - a_ud_{vy})\,\mathbf e_{4315} \\ +\, &(a_yd_{mx} - a_xd_{my} + a_wd_{pz} - a_ud_{vz})\,\mathbf e_{4125} \\ +\, &(a_ud_{pw} - a_xd_{px} - a_yd_{py} - a_zd_{pz})\,\mathbf e_{3215} \end{split}$$
Sphere containing round point $$\mathbf a$$ and centered at flat point $$\mathbf p$$. $$\begin{split}\mathbf a \wedge \mathbf p^\unicode["segoe ui symbol"]{x2606} = -\, &a_wp_w \mathbf e_{1234} + a_wp_x \mathbf e_{4235} + a_wp_y \mathbf e_{4315} + a_wp_z \mathbf e_{4125} \\ +\, &(a_up_w - a_xp_x - a_yp_y - a_zp_z)\,\mathbf e_{3215} \end{split}$$

See Also

• Join and meet
• Exterior products