Real coordinate space
(重定向自Usual topology)




In mathematics, real coordinate space of n dimensions, written R (/ɑːrˈɛn/ ar-EN) (R with superscript n, also written ℝ with blackboard bold R) or R^n with keyboard is a coordinate space that allows several (n) real variables to be treated as a single variable. With various numbers of dimensions (sometimes unspecified), R is used in many areas of pure and applied mathematics, as well as in physics. It is the prototypical real vector space and a frequently used representation of Euclidean n-space. Due to the latter fact, geometric metaphors are widely used for R, namely a plane for R and three-dimensional space for R.