Conical coordinates

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Coordinate surfaces of the conical coordinates. The constants b and c were chosen as 1 and 2, respectively. The red sphere represents r = 2, the blue elliptic cone aligned with the vertical z-axis represents μ=cosh(1) and the yellow elliptic cone aligned with the (green) x-axis corresponds to ν2 = 2/3. The three surfaces intersect at the point P (shown as a black sphere) with Cartesian coordinates roughly (1.26, -0.78, 1.34). The elliptic cones intersect the sphere in taco-shaped curves.

Conical coordinates are a three-dimensional orthogonal coordinate system consisting of concentric spheres (described by their radius r) and by two families of perpendicular cones, aligned along the z- and x-axes, respectively.

Basic definitions[edit]

The conical coordinates are defined by

with the following limitations on the coordinates

Surfaces of constant r are spheres of that radius centered on the origin

whereas surfaces of constant and are mutually perpendicular cones


In this coordinate system, both Laplace's equation and the Helmholtz equation are separable.

Scale factors[edit]

The scale factor for the radius r is one (hr = 1), as in spherical coordinates. The scale factors for the two conical coordinates are


Alternate Definition[edit]


An alternative set of conical coordinates have been derived[1]

where are spherical polar coordinates. The corresponding inverse relations are

The infinitesimal Euclidean distance between two points in these coordinates

If the path between any two points is constrained to surface of the cone given by then the geodesic distance between any two points

and is


  1. ^ Drake, Samuel Picton; Anderson, Brian D. O.; Yu, Changbin (2009-07-20). "Causal association of electromagnetic signals using the Cayley–Menger determinant". Applied Physics Letters. 95 (3): 034106. doi:10.1063/1.3180815. ISSN 0003-6951. 


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External links[edit]