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  2. Dilation (metric space) - Wikipedia

    en.wikipedia.org/wiki/Dilation_(metric_space)

    [1] In Euclidean space, such a dilation is a similarity of the space. [2] Dilations change the size but not the shape of an object or figure. Every dilation of a Euclidean space that is not a congruence has a unique fixed point [3] that is called the center of dilation. [4] Some congruences have fixed points and others do not. [5]

  3. Scale invariance - Wikipedia

    en.wikipedia.org/wiki/Scale_invariance

    In physics, mathematics and statistics, scale invariance is a feature of objects or laws that do not change if scales of length, energy, or other variables, are multiplied by a common factor, and thus represent a universality. The technical term for this transformation is a dilatation (also known as dilation).

  4. Jefimenko's equations - Wikipedia

    en.wikipedia.org/wiki/Jefimenko's_equations

    The formula provides a natural generalization of the Coulomb's law for cases where the source charge is moving: = [′ ′ + ′ (′ ′) + ′] = ′ Here, and are the electric and magnetic fields respectively, is the electric charge, is the vacuum permittivity (electric field constant) and is the speed of light.

  5. Contraction (operator theory) - Wikipedia

    en.wikipedia.org/wiki/Contraction_(operator_theory)

    Then the minimal unitary dilation U of T on K ⊃ H is unitarily equivalent to a direct sum of copies the bilateral shift operator, i.e. multiplication by z on L 2 (S 1). [5] If P is the orthogonal projection onto H then for f in L ∞ = L ∞ (S 1) it follows that the operator f(T) can be defined by = ().

  6. Homothety - Wikipedia

    en.wikipedia.org/wiki/Homothety

    k = −1 corresponds to a point reflection at point S Homothety of a pyramid. In mathematics, a homothety (or homothecy, or homogeneous dilation) is a transformation of an affine space determined by a point S called its center and a nonzero number k called its ratio, which sends point X to a point X ′ by the rule, [1]

  7. Length contraction - Wikipedia

    en.wikipedia.org/wiki/Length_contraction

    In the second method, times and are not equal due to time dilation, resulting in different lengths too. The deviation between the measurements in all inertial frames is given by the formulas for Lorentz transformation and time dilation (see Derivation). It turns out that the proper length remains unchanged and always denotes the greatest length ...

  8. Dilation - Wikipedia

    en.wikipedia.org/wiki/Dilation

    Dilation (operator theory), a dilation of an operator on a Hilbert space; Dilation (morphology), an operation in mathematical morphology; Scaling (geometry), including: Homogeneous dilation , the scalar multiplication operator on a vector space or affine space; Inhomogeneous dilation, where scale factors may differ in different directions

  9. Dilation (morphology) - Wikipedia

    en.wikipedia.org/wiki/Dilation_(morphology)

    Dilation (usually represented by ⊕) is one of the basic operations in mathematical morphology. Originally developed for binary images, it has been expanded first to grayscale images, and then to complete lattices. The dilation operation usually uses a structuring element for probing and expanding the shapes contained in the input image.