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  2. Vertex distance - Wikipedia

    en.wikipedia.org/wiki/Vertex_distance

    Vertex distance. Vertex distance is the distance between the back surface of a corrective lens, i.e. glasses (spectacles) or contact lenses, and the front of the cornea. Increasing or decreasing the vertex distance changes the optical properties of the system, by moving the focal point forward or backward, effectively changing the power of the ...

  3. NodeXL - Wikipedia

    en.wikipedia.org/wiki/NodeXL

    Graph metrics and edge and vertex visual properties appear as additional columns in the respective worksheets. This representation allows the user to leverage the Excel spreadsheet to quickly edit existing node properties and to generate new ones, for instance by applying Excel formulas to existing columns.

  4. Wiener index - Wikipedia

    en.wikipedia.org/wiki/Wiener_index

    Butane (C 4 H 10) has two different structural isomers: n-butane, with a linear structure of four carbon atoms, and isobutane, with a branched structure.The chemical graph for n-butane is a four-vertex path graph, and the chemical graph for isobutane is a tree with one central vertex connected to three leaves.

  5. Anisometropia - Wikipedia

    en.wikipedia.org/wiki/Anisometropia

    F = back vertex power (in 1/metres), (essentially, the prescription for the lens, quoted in diopters). If the difference between the eyes is up to 3 diopters, iseikonic lenses can compensate. At a difference of 3 diopters the lenses would however be very visibly different—one lens would need to be at least 3 mm thicker and have a base curve ...

  6. Sagitta (optics) - Wikipedia

    en.wikipedia.org/wiki/Sagitta_(optics)

    The sag S(r) is the displacement along the optic axis of the surface from the vertex, at distance from the axis. A good explanation both of this approximate formula and the exact formula can be found here .

  7. Radius of curvature (optics) - Wikipedia

    en.wikipedia.org/wiki/Radius_of_curvature_(optics)

    where the optic axis is presumed to lie in the z direction, and () is the sag—the z-component of the displacement of the surface from the vertex, at distance from the axis. If α 1 {\displaystyle \alpha _{1}} and α 2 {\displaystyle \alpha _{2}} are zero, then R {\displaystyle R} is the radius of curvature and K {\displaystyle K} is the conic ...

  8. Vincenty's formulae - Wikipedia

    en.wikipedia.org/wiki/Vincenty's_formulae

    Vincenty's formulae are two related iterative methods used in geodesy to calculate the distance between two points on the surface of a spheroid, developed by Thaddeus Vincenty (1975a). They are based on the assumption that the figure of the Earth is an oblate spheroid, and hence are more accurate than methods that assume a spherical Earth, such ...

  9. Metric k-center - Wikipedia

    en.wikipedia.org/wiki/Metric_k-center

    In graph theory, the metric k-center problem or vertex k-center problem is a classical combinatorial optimization problem studied in theoretical computer science that is NP-hard. Given n cities with specified distances, one wants to build k warehouses in different cities and minimize the maximum distance of a city to a warehouse.