of a point $P$ in three-dimensional space
Numbers $x_1,x_2,x_3,x_4$ which are proportional (with given coefficient of proportionality) to the distances from $P$ to the faces of a fixed tetrahedron, not necessarily regular. Analogously, one may introduce general normal coordinates for any dimension. The two-dimensional analogues of tetrahedral coordinates are called trilinear coordinates. See also Barycentric coordinates.
|[a1]||H.S.M. Coxeter, "Regular polytopes" , Dover, reprint (1973) pp. 183|
Tetrahedral coordinates. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Tetrahedral_coordinates&oldid=31739