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  2. Positive operator - Wikipedia

    en.wikipedia.org/wiki/Positive_operator

    In mathematics (specifically linear algebra, operator theory, and functional analysis) as well as physics, a linear operator acting on an inner product space is called positive-semidefinite (or non-negative) if, for every ⁡ (), , and , , where ⁡ is the domain of .

  3. Sylvester's criterion - Wikipedia

    en.wikipedia.org/wiki/Sylvester's_criterion

    In mathematics, Sylvester’s criterion is a necessary and sufficient criterion to determine whether a Hermitian matrix is positive-definite. Sylvester's criterion states that a n × n Hermitian matrix M is positive-definite if and only if all the following matrices have a positive determinant: the upper left 1-by-1 corner of M,

  4. Positive semidefinite - Wikipedia

    en.wikipedia.org/wiki/Positive_semidefinite

    In mathematics, positive semidefinite may refer to: Positive semidefinite function; Positive semidefinite matrix; Positive semidefinite quadratic form;

  5. Moment problem - Wikipedia

    en.wikipedia.org/wiki/Moment_problem

    A sequence of numbers is the sequence of ... This is because a positive-semidefinite Hankel matrix corresponds to a linear functional ...

  6. Conjugate gradient method - Wikipedia

    en.wikipedia.org/wiki/Conjugate_gradient_method

    The conjugate gradient method can be applied to an arbitrary n-by-m matrix by applying it to normal equations A T A and right-hand side vector A T b, since A T A is a symmetric positive-semidefinite matrix for any A. The result is conjugate gradient on the normal equations (CGN or CGNR). A T Ax = A T b

  7. Mercer's theorem - Wikipedia

    en.wikipedia.org/wiki/Mercer's_theorem

    Mercer's theorem itself is a generalization of the result that any symmetric positive-semidefinite matrix is the Gramian matrix of a set of vectors. The first generalization replaces the interval [ a , b ] with any compact Hausdorff space and Lebesgue measure on [ a , b ] is replaced by a finite countably additive measure μ on the Borel ...

  8. Positive-definite function - Wikipedia

    en.wikipedia.org/wiki/Positive-definite_function

    One can define positive-definite functions on any locally compact abelian topological group; Bochner's theorem extends to this context. Positive-definite functions on groups occur naturally in the representation theory of groups on Hilbert spaces (i.e. the theory of unitary representations).

  9. Gram matrix - Wikipedia

    en.wikipedia.org/wiki/Gram_matrix

    Given any positive semidefinite matrix , one can decompose it as: = †, where † is the ... to the sequence of vectors results in the same Gram matrix. That is, ...