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Conical Coordinates


ConicalCoordinates

There are several different definitions of conical coordinates defined by Morse and Feshbach (1953), Byerly (1959), Arfken (1970), and Moon and Spencer (1988). The (lambda,mu,nu) system defined in the Wolfram Language is

x=(lambdamunu)/(ab)
(1)
y=lambda/asqrt(((mu^2-a^2)(nu^2-a^2))/(a^2-b^2))
(2)
z=lambda/bsqrt(((mu^2-b^2)(nu^2-b^2))/(b^2-a^2)),
(3)

where b^2>mu^2>c^2>nu^2. Byerly (1959) uses a (r,mu,nu) system which is essentially the same coordinate system as above, but replacing lambda with r, a with b, and b with c. Moon and Spencer (1988) use (r,theta,lambda) instead of (lambda,mu,nu).

The above equations give

 x^2+y^2+z^2=lambda^2
(4)
 (x^2)/(mu^2)+(y^2)/(mu^2-a^2)+(z^2)/(mu^2-b^2)=0
(5)
 (x^2)/(nu^2)+(y^2)/(nu^2-a^2)+(z^2)/(nu^2-b^2)=0.
(6)

The scale factors are

h_lambda=1
(7)
h_mu=sqrt((lambda^2(mu^2-nu^2))/((mu^2-a^2)(b^2-mu^2)))
(8)
h_nu=sqrt((lambda^2(mu^2-nu^2))/((nu^2-a^2)(nu^2-b^2))).
(9)

The Laplacian is

 del ^2=(nu(2nu^2-a^2-b^2))/((mu-nu)(mu+nu)lambda^2)partial/(partialnu)+((a-nu)(a+nu)(nu-b)(nu+b))/((nu-mu)(nu+mu)lambda^2)(partial^2)/(partialnu^2) 
 +(mu(2mu^2-a^2-b^2))/((nu-mu)(nu+mu)lambda^2)partial/(partialmu)+((mu-b)(mu+b)(mu-a)(mu+a))/((nu-mu)(nu+mu)lambda^2)(partial^2)/(partialmu^2)+2/lambdapartial/(partiallambda)+(partial^2)/(partiallambda^2).
(10)

The Helmholtz differential equation is separable in conical coordinates.


See also

Helmholtz Differential Equation--Conical Coordinates

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References

Arfken, G. "Conical Coordinates (xi_1, xi_2, xi_3)." §2.16 in Mathematical Methods for Physicists, 2nd ed. Orlando, FL: Academic Press, pp. 118-119, 1970.Byerly, W. E. An Elementary Treatise on Fourier's Series, and Spherical, Cylindrical, and Ellipsoidal Harmonics, with Applications to Problems in Mathematical Physics. New York: Dover, p. 263, 1959.Moon, P. and Spencer, D. E. "Conical Coordinates (r,theta,lambda)." Table 1.09 in Field Theory Handbook, Including Coordinate Systems, Differential Equations, and Their Solutions, 2nd ed. New York: Springer-Verlag, pp. 37-40, 1988.Morse, P. M. and Feshbach, H. Methods of Theoretical Physics, Part I. New York: McGraw-Hill, p. 659, 1953.Spence, R. D. "Angular Momentum in Sphero-Conal Coordinates." Amer. J. Phys. 27, 329-335, 1959.

Referenced on Wolfram|Alpha

Conical Coordinates

Cite this as:

Weisstein, Eric W. "Conical Coordinates." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ConicalCoordinates.html

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