Coordinate system 坐标系
(重定向自Coord)
The simplest example of a coordinate system is the identification of points on a line with real numbers using the
number line. In this system, an arbitrary point
O (the
origin) is chosen on a given line. The coordinate of a point
P is defined as the signed distance from
O to
P, where the signed distance is the distance taken as positive or negative depending on which side of the line
P lies. Each point is given a unique coordinate and each real number is the coordinate of a unique point.
Cartesian coordinate system
The prototypical example of a coordinate system is the Cartesian coordinate system. In the plane, two perpendicular lines are chosen and the coordinates of a point are taken to be the signed distances to the lines.
In three dimensions, three perpendicular planes are chosen and the three coordinates of a point are the signed distances to each of the planes. This can be generalized to create n coordinates for any point in n-dimensional Euclidean space.