The x-axis is the north-south direction; The greater the value of x on the coordinate, the farther north the point is, the smaller the data of x is, and the farther south the point is.

Y axis is the east-west direction; The greater the value of y on the coordinate, the more eastward the point, the smaller the data of y, and the more westward the point.

Two number axes intersecting at the origin form a plane radiation coordinate system. If the units of measurement on two axes are equal, this radial coordinate system is called Cartesian coordinate system.

A Cartesian coordinate system with two vertical axes is called Cartesian Cartesian coordinate system, otherwise it is called Cartesian oblique coordinate system. It should be pointed out that the Cartesian coordinate system in mathematics should be distinguished from the Cartesian coordinate system in the movie kill array in Different Dimensions. The definition in the movie is different from that in mathematics, so please don't confuse it.

Spherical coordinate system (sphere):

Suppose that P(x, y, z) is a point in space, and the point p can also be determined by such three ordered numbers (r, θ, φ), where r is the distance from the origin o to the point p; θ is the included angle between the directed line segment OP and the positive direction of Z axis.

φ is the angle from X axis to om counterclockwise when viewed from the positive direction of Z axis, where m is the projection of point P on xOy plane. Such three numbers R, θ and φ are called the spherical coordinates of point P. Obviously, the value ranges of R, θ and φ here are r∈[0, +∞], θ∈[0, π] and φ∈[0, 2π].