PlanetMath: spherical coordinates

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spherical coordinates

(Definition)

Spherical coordinates are a system of coordinates for $\mathbb{R}^3$ , or more generally $\mathbb{R}^n$ . One coordinate is the distance from the origin, which can be thought of as the radius of the sphere centred at the origin on which the point lies. The other coordinates are angles that specify the position of the point on this sphere.

In $\mathbb{R}^3$ the coordinates are given by

$\displaystyle \left( \begin{tabular}{c} $x$\\ $y$\\ $z$ \end{tabular}\right)$

$\displaystyle = \left( \begin{tabular}{c} $r\sin\phi\cos\theta$\\ $r\sin\phi\sin\theta$\\ $r\cos\phi$ \end{tabular} \right),$

where

is the distance from the origin, $\theta$ is the azimuthal angle defined for $\theta\in[0,2\pi)$ , and $\phi\in[0,\pi]$ is the polar angle. Note that $\phi=0$ corresponds to the top of the sphere and $\phi=\pi$ corresponds to the bottom of the sphere. There is a clash between the mathematicians' and the physicists' definition of spherical coordinates, interchanging both the direction of $\phi$ and the choice of names for the two angles (physicists often use $\theta$ as the azimuthal angle and $\phi$ as the polar one).

Spherical coordinates are a generalization of polar coordinates, and can be further generalized to $\mathbb{R}^n$ , with polar angles $\phi_1,\ldots,\phi_{n-2}$ and one azimuthal angle $\theta$ :

$\displaystyle \left( \begin{tabular}{c} $x_1$\\ $x_2$\\ $\vdots$\\ $x_k$\\ $\vdots$\\ $x_{n-1}$\\ $x_n$ \end{tabular}\right)$

$\displaystyle = \left( \begin{tabular}{c} $r\cos\phi_1$\\ $r\sin\phi_1\cos\phi_... ...\ $r\sin\phi_1\sin\phi_2\cdots\sin\phi_{n-2}\sin\theta$. \end{tabular} \right).$

These are sometimes called hyperspherical coordinates if .

"spherical coordinates" is owned by yark. [ full author list (2) | owner history (1) ]

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See Also: sphere, cylindrical coordinates

Also defines:

hyperspherical coordinates, azimuthal angle, polar angle

Keywords:

sphere

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Cross-references: polar coordinates, angles, point, sphere, radius, origin, distance, coordinates
There are 19 references to this entry.

This is version 9 of spherical coordinates, born on 2003-07-22, modified 2007-05-05.
Object id is 4491, canonical name is SphericalCoordinates.
Accessed 11693 times total.

Classification:

AMS MSC:

51M05 (Geometry :: Real and complex geometry :: Euclidean geometries and generalizations)

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