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In geometry, a point is an abstract idealization of an exact position, without size, in physical space, [1] or its generalization to other kinds of mathematical spaces.As zero-dimensional objects, points are usually taken to be the fundamental indivisible elements comprising the space, of which one-dimensional curves, two-dimensional surfaces, and higher-dimensional objects consist; conversely ...
In typography, the point is the smallest unit of measure. It is used for measuring font size, leading, and other items on a printed page. The size of the point has varied throughout printing's history. Since the 18th century, the size of a point has been between 0.18 and 0.4 millimeters.
The Didot point was metrically redefined as 1 ⁄ 2660 m (≈ 0.376 mm) [citation needed] in 1879 by Berthold. The advent and success of desktop publishing (DTP) software and word processors for office use, coming mostly from the non-metric United States , side stepped this metrication process in typography.
A point particle is an appropriate representation of any object whenever its size, shape, and structure are irrelevant in a given context. For example, from far enough away, any finite-size object will look and behave as a point-like object. Point masses and point charges, discussed below, are two common cases.
For example, "agate" and "ruby" used to be a single size "agate ruby" of about 5 points; [2] metal type known as "agate" later ranged from 5 to 5.8 points. The sizes were gradually standardized as described above. [3] Modern Chinese typography uses the following names in general preference to stating the number of points.
The vanishing point may also be referred to as the "direction point", as lines having the same directional vector, say D, will have the same vanishing point. Mathematically, let q ≡ ( x , y , f ) be a point lying on the image plane, where f is the focal length (of the camera associated with the image), and let v q ≡ ( x / h , y ...
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A set with no isolated point is said to be dense-in-itself (every neighbourhood of a point contains other points of the set). A closed set with no isolated point is called a perfect set (it contains all its limit points and no isolated points). The number of isolated points is a topological invariant, i.e. if two topological spaces X, Y are ...