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  2. Levi-Civita symbol - Wikipedia

    en.wikipedia.org/wiki/Levi-Civita_symbol

    The formula is valid for all index values, and for any n (when n = 0 or n = 1, this is the empty product). However, computing the formula above naively has a time complexity of O( n 2 ) , whereas the sign can be computed from the parity of the permutation from its disjoint cycles in only O( n log( n )) cost.

  3. Quaternion - Wikipedia

    en.wikipedia.org/wiki/Quaternion

    Because the product of any two basis vectors is plus or minus another basis vector, the set {±1, ±i, ±j, ±k} forms a group under multiplication. This non- abelian group is called the quaternion group and is denoted Q 8 . [ 26 ]

  4. Quaternion group - Wikipedia

    en.wikipedia.org/wiki/Quaternion_group

    In the diagrams for D 4, the group elements are marked with their action on a letter F in the defining representation R 2. The same cannot be done for Q 8, since it has no faithful representation in R 2 or R 3. D 4 can be realized as a subset of the split-quaternions in the same way that Q 8 can be viewed as a subset of the quaternions.

  5. Levi-Civita connection - Wikipedia

    en.wikipedia.org/wiki/Levi-Civita_connection

    The metric g can take up to two vectors or vector fields X, Y as arguments. In the former case the output is a number, the (pseudo-)inner product of X and Y. In the latter case, the inner product of X p, Y p is taken at all points p on the manifold so that g(X, Y) defines a smooth function on M. Vector fields act (by definition) as differential ...

  6. Versor - Wikipedia

    en.wikipedia.org/wiki/Versor

    In mathematics, a versor is a quaternion of norm one (a unit quaternion).Each versor has the form = ⁡ = ⁡ + ⁡, =, [,], where the r 2 = −1 condition means that r is a unit-length vector quaternion (or that the first component of r is zero, and the last three components of r are a unit vector in 3 dimensions).

  7. Hypercomplex number - Wikipedia

    en.wikipedia.org/wiki/Hypercomplex_number

    The first algebras in this sequence include the 4-dimensional quaternions, 8-dimensional octonions, and 16-dimensional sedenions. An algebraic symmetry is lost with each increase in dimensionality: quaternion multiplication is not commutative , octonion multiplication is non- associative , and the norm of sedenions is not multiplicative.

  8. List of formulas in Riemannian geometry - Wikipedia

    en.wikipedia.org/wiki/List_of_formulas_in...

    6.4 Scalar curvature. 6.5 Traceless Ricci tensor. 6.6 ... The variation formula computations above define the principal symbol of the mapping which sends a pseudo ...

  9. Quaternions and spatial rotation - Wikipedia

    en.wikipedia.org/wiki/Quaternions_and_spatial...

    3D visualization of a sphere and a rotation about an Euler axis (^) by an angle of In 3-dimensional space, according to Euler's rotation theorem, any rotation or sequence of rotations of a rigid body or coordinate system about a fixed point is equivalent to a single rotation by a given angle about a fixed axis (called the Euler axis) that runs through the fixed point. [6]