Meaning of quadratic form | Babel Free

Definitions

1. A homogeneous polynomial of degree 2 in a given number of variables.
2. A scalar quantity of the form εᵀΛε, where ε is a vector of n random variables, and Λ is an n-dimensional symmetric matrix.

Equivalents

Examples

“Historically, quadratic form⟳ theory has been treated as a rich but misunderstood uncle.”

“2004, Nikita A. Karpenko, Izhboldin's Results on Stably Birational of Equivalence Quadrics, Oleg T. Izhboldin, Geometric Methods in the Algebraic Theory of Quadratic Forms, Springer, Lecture⟳ Notes in Mathematics 1835, page 156, We claim⟳ that this quadratic form⟳ is isotropic, and this gives what we need⟳ according to [2, Proposition 4.4].”

“2009, R. Parimala, V. Suresh, J.-P. Tignol, On the Pfister Number⟳ of Quadratic Forms, Ricardo Baeza, Quadratic Forms—Algebra, Arithmetic, and Geometry, American Mathematical Society, page 327, The generic quadratic form⟳ of even dimension n with trivial discriminant over an arbitrary field of characteristic different from 2 containing a square root of −1 can be written in the Witt ring⟳ as a sum of 2-fold⟳ Pfister forms using n − 2 terms and not less. The number⟳ of Pfister forms required to express⟳ a quadratic form⟳ of degree 6 with trivial discriminant is determined in various cases.”

“The arithmetic theory of binary quadratic forms, which had its origins in the work⟳ of Fermat, was extensively developed during the 18th century by Euler, Lagrange, Legendre and Gauss. The extension to quadratic forms in more than two variables, which was begun by them and is exemplified by Lagrange's theorem that every positive integer is a sum of four squares, was continued in the 19th century by Dirichlet, Hermite, H. J. S. Smith, Minkowski and others.”

“Quadratic forms of normal random vectors are of great importance in many branches of statistics, such as least-squares methods, the analysis of variance, regression analysis, and experimental design⟳.”

CEFR level