A coordinate system similar to toroidal coordinates but with fourth-degree instead of second-degree surfaces for constant so that the toroids of circular cross
section are replaced by flattened rings, and the spherical bowls are replaced
by cyclides of rotation for constant
. The transformation equations are
(1)
| |||
(2)
| |||
(3)
|
where
(4)
|
and with ,
,
and
.
Surfaces of constant
are given by the flat-ring cyclides
(5)
|
surfaces of constant by the cyclides of rotation
(6)
|
and surfaces of constant by the half-planes
(7)
|