Vectors (mathematics and physics) | Polytopes

Eutactic star

In Euclidean geometry, a eutactic star is a geometrical figure in a Euclidean space. A star is a figure consisting of any number of opposing pairs of vectors (or arms) issuing from a central origin. A star is eutactic if it is the orthogonal projection of plus and minus the set of standard basis vectors (i.e., the vertices of a cross-polytope) from a higher-dimensional space onto a subspace. Such stars were called "eutactic" – meaning "well-situated" or "well-arranged" – by , p. 134) because, for a common scalar multiple, their vectors are projections of an orthonormal basis. (Wikipedia).

Eutactic star
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Related pages

Polytope | Perpendicular | Euclidean geometry | If and only if | Unit vector | Orthogonal transformation | Parallel (geometry) | Group (mathematics) | Eutactic lattice | Polarization identity | Cross-polytope | Orthonormal basis | Euclidean space | Scalar (mathematics) | Symmetric matrix | Projection (mathematics) | Euclidean vector | Matrix (mathematics) | Irreducible representation