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  2. Cartesian coordinate system - Wikipedia

    en.wikipedia.org/wiki/Cartesian_coordinate_system

    Cartesian coordinate system with a circle of radius 2 centered at the origin marked in red. The equation of a circle is (x − a)2 + (y − b)2 = r2 where a and b are the coordinates of the center (a, b) and r is the radius. Cartesian coordinates are named for René Descartes, whose invention of them in the 17th century revolutionized ...

  3. Map (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Map_(mathematics)

    Map (mathematics) A map is a function, as in the association of any of the four colored shapes in X to its color in Y. In mathematics, a map or mapping is a function in its general sense. [1] These terms may have originated as from the process of making a geographical map: mapping the Earth surface to a sheet of paper.

  4. Closed graph theorem - Wikipedia

    en.wikipedia.org/wiki/Closed_graph_theorem

    Closed graph theorem [5] — If : is a map from a topological space into a Hausdorff space, then the graph of is closed if : is continuous. The converse is true when Y {\displaystyle Y} is compact .

  5. Graph of a function - Wikipedia

    en.wikipedia.org/wiki/Graph_of_a_function

    Given a function: from a set X (the domain) to a set Y (the codomain), the graph of the function is the set [4] = {(, ()):}, which is a subset of the Cartesian product.In the definition of a function in terms of set theory, it is common to identify a function with its graph, although, formally, a function is formed by the triple consisting of its domain, its codomain and its graph.

  6. Equirectangular projection - Wikipedia

    en.wikipedia.org/wiki/Equirectangular_projection

    Equirectangular projection. Equirectangular projection of the world; the standard parallel is the equator (plate carrée projection). Height map of planet Earth at 2km per pixel, including oceanic bathymetry information, normalized as 8-bit grayscale. Because of its easy conversion between x, y pixel information and lat-lon, maps like these are ...

  7. Closed graph property - Wikipedia

    en.wikipedia.org/wiki/Closed_graph_property

    Closed graph property. In mathematics, particularly in functional analysis and topology, closed graph is a property of functions. [1][2] A function f : XY between topological spaces has a closed graph if its graph is a closed subset of the product space X × Y. A related property is open graph. [3]

  8. Projected coordinate system - Wikipedia

    en.wikipedia.org/wiki/Projected_coordinate_system

    Geodesy. A projected coordinate system – also called a projected coordinate reference system, planar coordinate system, or grid reference system – is a type of spatial reference system that represents locations on Earth using Cartesian coordinates (x, y) on a planar surface created by a particular map projection. [1]

  9. Open and closed maps - Wikipedia

    en.wikipedia.org/wiki/Open_and_closed_maps

    Open and closed maps. In mathematics, more specifically in topology, an open map is a function between two topological spaces that maps open sets to open sets. [1][2][3] That is, a function is open if for any open set in the image is open in Likewise, a closed map is a function that maps closed sets to closed sets. [3][4] A map may be open ...