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Oriented Plane Segment
In mathematics, a bivector or 2-vector is a quantity in exterior algebra or geometric algebra that extends the idea of scalars and vectors. Considering a scalar as a degree-zero quantity and a vector as a degree-one quantity, a bivector is of degree two. Bivectors have applications in many areas of mathematics and physics. They are related to complex numbers in two dimensions and to both pseudovectors and vector quaternions in three dimensions. They can be used to generate rotations in a space of any number of dimensions, and are a useful tool for classifying such rotations. Geometrically, a simple bivector can be interpreted as characterizing a directed plane segment (or oriented plane segment), much as vectors can be thought of as characterizing ''directed line segments''. The bivector has an ''attitude'' (or direction) of the plane spanned by and , has an area that is a scalar multiple of any reference plane segment with the same attitude (and in geometric algebra, it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivector (complex)
In mathematics, a bivector is the vector part of a biquaternion. For biquaternion , ''w'' is called the biscalar and is its bivector part. The coordinates ''w'', ''x'', ''y'', ''z'' are complex numbers with imaginary unit h: :x = x_1 + \mathrm x_2,\ y = y_1 + \mathrm y_2,\ z = z_1 + \mathrm z_2, \quad \mathrm^2 = -1 = \mathrm^2 = \mathrm^2 = \mathrm^2 . A bivector may be written as the sum of real and imaginary parts: :(x_1 \mathrm + y_1 \mathrm + z_1 \mathrm) + \mathrm (x_2 \mathrm + y_2 \mathrm + z_2 \mathrm) where r_1 = x_1 \mathrm + y_1 \mathrm + z_1 \mathrm and r_2 = x_2 \mathrm + y_2 \mathrm + z_2 \mathrm are vectors. Thus the bivector q = x \mathrm + y \mathrm + z \mathrm = r_1 + \mathrm r_2 . Link from David R. Wilkins collection at Trinity College, Dublin The Lie algebra of the Lorentz group is expressed by bivectors. In particular, if ''r''1 and ''r''2 are right versors so that r_1^2 = -1 = r_2^2, then the biquaternion curve traces over and over the unit circle in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnitude (mathematics)
In mathematics, the magnitude or size of a mathematical object is a property which determines whether the object is larger or smaller than other objects of the same kind. More formally, an object's magnitude is the displayed result of an ordering (or ranking) of the class of objects to which it belongs. Magnitude as a concept dates to Ancient Greece and has been applied as a measure of distance from one object to another. For numbers, the absolute value of a number is commonly applied as the measure of units between a number and zero. In vector spaces, the Euclidean norm is a measure of magnitude used to define a distance between two points in space. In physics, magnitude can be defined as quantity or distance. An order of magnitude is typically defined as a unit of distance between one number and another's numerical places on the decimal scale. History Ancient Greeks distinguished between several types of magnitude, including: * Positive fractions * Line segments (orde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry Forder
Henry George Forder (27 September 1889 – 21 September 1981) was a New Zealand mathematician. Academic career Born in Shotesham All Saints, near Norwich, he won a scholarships first to a Grammar school and then to University of Cambridge. After teaching mathematics at a number of schools, he was appointed to the chair of mathematics at Auckland University College in New Zealand in 1933. He was very critical of the state of the New Zealand curriculum and set about writing a series of well received textbooks. His ''Foundations of Euclidean Geometry'' (1927) was reviewed by F.W. Owens, who noted that 40 pages are devoted to "concepts of classes, relations, linear order, non archimedean systems, ..." and that order axioms together with a continuity axiom and a Euclidean parallel axiom are the required foundation. The object achieved is a "continuous and rigorous development of the uclideandoctrine in the light of modern investigations." In 1929 Forder obtained drawings and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clifford Algebra
In mathematics, a Clifford algebra is an algebra generated by a vector space with a quadratic form, and is a unital associative algebra with the additional structure of a distinguished subspace. As -algebras, they generalize the real numbers, complex numbers, quaternions and several other hypercomplex number systems. The theory of Clifford algebras is intimately connected with the theory of quadratic forms and orthogonal transformations. Clifford algebras have important applications in a variety of fields including geometry, theoretical physics and digital image processing. They are named after the English mathematician William Kingdon Clifford (1845–1879). The most familiar Clifford algebras, the orthogonal Clifford algebras, are also referred to as (''pseudo-'')''Riemannian Clifford algebras'', as distinct from ''symplectic Clifford algebras''. Introduction and basic properties A Clifford algebra is a unital associative algebra that contains and is generated by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Kingdon Clifford
William Kingdon Clifford (4 May 18453 March 1879) was a British mathematician and philosopher. Building on the work of Hermann Grassmann, he introduced what is now termed geometric algebra, a special case of the Clifford algebra named in his honour. The operations of geometric algebra have the effect of mirroring, rotating, translating, and mapping the geometric objects that are being modelled to new positions. Clifford algebras in general and geometric algebra in particular have been of ever increasing importance to mathematical physics, geometry, and computing. Clifford was the first to suggest that gravitation might be a manifestation of an underlying geometry. In his philosophical writings he coined the expression ''mind-stuff''. Biography Born in Exeter, William Clifford was educated at Doctor Templeton's Academy on Bedford Circus and showed great promise at school. He went on to King's College London (at age 15) and Trinity College, Cambridge, where he was elected fello ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bivector (complex)
In mathematics, a bivector is the vector part of a biquaternion. For biquaternion , ''w'' is called the biscalar and is its bivector part. The coordinates ''w'', ''x'', ''y'', ''z'' are complex numbers with imaginary unit h: :x = x_1 + \mathrm x_2,\ y = y_1 + \mathrm y_2,\ z = z_1 + \mathrm z_2, \quad \mathrm^2 = -1 = \mathrm^2 = \mathrm^2 = \mathrm^2 . A bivector may be written as the sum of real and imaginary parts: :(x_1 \mathrm + y_1 \mathrm + z_1 \mathrm) + \mathrm (x_2 \mathrm + y_2 \mathrm + z_2 \mathrm) where r_1 = x_1 \mathrm + y_1 \mathrm + z_1 \mathrm and r_2 = x_2 \mathrm + y_2 \mathrm + z_2 \mathrm are vectors. Thus the bivector q = x \mathrm + y \mathrm + z \mathrm = r_1 + \mathrm r_2 . Link from David R. Wilkins collection at Trinity College, Dublin The Lie algebra of the Lorentz group is expressed by bivectors. In particular, if ''r''1 and ''r''2 are right versors so that r_1^2 = -1 = r_2^2, then the biquaternion curve traces over and over the unit circle in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biquaternion
In abstract algebra, the biquaternions are the numbers , where , and are complex numbers, or variants thereof, and the elements of multiply as in the quaternion group and commute with their coefficients. There are three types of biquaternions corresponding to complex numbers and the variations thereof: * Biquaternions when the coefficients are complex numbers. * Split-biquaternions when the coefficients are split-complex numbers. * Dual quaternions when the coefficients are dual numbers. This article is about the ''ordinary biquaternions'' named by William Rowan Hamilton in 1844. Some of the more prominent proponents of these biquaternions include Alexander Macfarlane, Arthur W. Conway, Ludwik Silberstein, and Cornelius Lanczos. As developed below, the unit quasi-sphere of the biquaternions provides a representation of the Lorentz group, which is the foundation of special relativity. The algebra of biquaternions can be considered as a tensor product of algebras, tensor product , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quaternions
In mathematics, the quaternion number system extends the complex numbers. Quaternions were first described by the Irish mathematician William Rowan Hamilton in 1843 and applied to mechanics in three-dimensional space. The algebra of quaternions is often denoted by (for ''Hamilton''), or in blackboard bold by \mathbb H. Quaternions are not a field, because multiplication of quaternions is not, in general, commutative. Quaternions provide a definition of the quotient of two vectors in a three-dimensional space. Quaternions are generally represented in the form a + b\,\mathbf i + c\,\mathbf j +d\,\mathbf k, where the coefficients , , , are real numbers, and , are the ''basis vectors'' or ''basis elements''. Quaternions are used in pure mathematics, but also have practical uses in applied mathematics, particularly for calculations involving three-dimensional rotations, such as in three-dimensional computer graphics, computer vision, robotics, magnetic resonance imaging and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Rowan Hamilton
Sir William Rowan Hamilton (4 August 1805 – 2 September 1865) was an Irish astronomer, mathematician, and physicist who made numerous major contributions to abstract algebra, classical mechanics, and optics. His theoretical works and mathematical equations are considered fundamental to modern theoretical physics, particularly Hamiltonian mechanics, his reformulation of Lagrangian mechanics. His career included the analysis of geometrical optics, Fourier analysis, and quaternions, the last of which made him one of the founders of modern linear algebra. Hamilton was Andrews Professor of Astronomy at Trinity College Dublin. He was also the third director of Dunsink Observatory from 1827 to 1865. The Hamilton Institute at Maynooth University is named after him. Early life Hamilton was the fourth of nine children born to Sarah Hutton (1780–1817) and Archibald Hamilton (1778–1819), who lived in Dublin at 29 Dominick Street, Dublin, Dominick Street, later renumbered to 36. Ham ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Grassmann
Hermann Günther Grassmann (, ; 15 April 1809 – 26 September 1877) was a German polymath known in his day as a linguist and now also as a mathematician. He was also a physicist, general scholar, and publisher. His mathematical work was little noted until he was in his sixties. His work preceded and exceeded the concept which is now known as a vector space. He introduced the Grassmannian, the space which parameterizes all ''k''-dimensional linear subspaces of an ''n''-dimensional vector space ''V''. In linguistics he helped free language history and structure from each other. Biography Hermann Grassmann was the third of 12 children of Justus Günter Grassmann, an ordained minister who taught mathematics and physics at the Stettin Gymnasium, where Hermann was educated. Grassmann was an undistinguished student until he obtained a high mark on the examinations for admission to Prussian universities. Beginning in 1827, he studied theology at the University of Berlin, also ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skew-symmetric Matrix
In mathematics, particularly in linear algebra, a skew-symmetric (or antisymmetric or antimetric) matrix is a square matrix whose transpose equals its negative. That is, it satisfies the condition In terms of the entries of the matrix, if a_ denotes the entry in the i-th row and j-th column, then the skew-symmetric condition is equivalent to Example The matrix A = \begin 0 & 2 & -45 \\ -2 & 0 & -4 \\ 45 & 4 & 0 \end is skew-symmetric because A^\textsf = \begin 0 & -2 & 45 \\ 2 & 0 & 4 \\ -45 & -4 & 0 \end = -A . Properties Throughout, we assume that all matrix entries belong to a field \mathbb whose characteristic is not equal to 2. That is, we assume that , where 1 denotes the multiplicative identity and 0 the additive identity of the given field. If the characteristic of the field is 2, then a skew-symmetric matrix is the same thing as a symmetric matrix. * The sum of two skew-symmetric matrices is skew-symmetric. * A scalar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antisymmetric Tensor
In mathematics and theoretical physics, a tensor is antisymmetric or alternating on (or with respect to) an index subset if it alternates sign (+/−) when any two indices of the subset are interchanged. section §7. The index subset must generally either be all ''covariant'' or all ''contravariant''. For example, T_ = -T_ = T_ = -T_ = T_ = -T_ holds when the tensor is antisymmetric with respect to its first three indices. If a tensor changes sign under exchange of ''each'' pair of its indices, then the tensor is completely (or totally) antisymmetric. A completely antisymmetric covariant tensor field of order k may be referred to as a differential k-form, and a completely antisymmetric contravariant tensor field may be referred to as a k-vector field. Antisymmetric and symmetric tensors A tensor A that is antisymmetric on indices i and j has the property that the contraction with a tensor B that is symmetric on indices i and j is identically 0. For a general tensor U with co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
