The name lemniscatic torus is used for several objects involving a lemniscate. In geometric modeling it denotes a surface of revolution generated from a lemniscate in a plane offset from the axis (Iglesias et al. 2013). In elliptic function theory it denotes the square complex torus (Cecotti and Vafa 2013, Eremenko 2023). A limiting solid of revolution whose meridian is a lemniscate also occurs in gravitational modeling (Zavizion 2006).
For the geometric construction, let and
, and define
|
(1)
| |||
|
(2)
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The plane curve satisfies the Bernoulli lemniscate
equation
|
(3)
|
where
is the half-width and the distance from the center to either focus
is
.
Rotating the curve
about the z-axis
gives
|
(4)
| |||
|
(5)
| |||
|
(6)
|
One lobe, with
and its endpoints identified, generates the entire surface
as
.
Using
covers the surface twice. The formulas above correct
the inconsistent half-width normalization and the first coordinate of the printed
rotation formula in Flores-Córdova et al. (2026, p. 118).
Eliminating the parameters gives the quartic surface
|
(7)
|
In cylindrical coordinates, with , a meridian
is parametrized by
|
(8)
|
and the bounds are
and
.
This meridian is generally not a Bernoulli lemniscate.
The generating lemniscate lies in the offset plane
, which does not contain the axis of
revolution.
For ,
the surface becomes an ordinary ring
torus with major radius
and tube radius
, so
(Iglesias et al. 2013). Its equation can be written
|
(9)
|
Curves on the geometric surface have been used to choose vertices for polyhedra
(Velezmoro-León et al. 2021, 2022) and, after orthogonal
projection onto a plane, control points for a wire
antenna (Flores-Córdova et al. 2026). Writing the parametric
equations above as , one useful family is
|
(10)
|
where
and
are positive integers and
. Its orthogonal
projection onto the
-plane has the complex
number representation
|
(11)
|
and satisfies
|
(12)
|
Thus relatively prime and
give
-fold rotational symmetry.
If
is a common integer factor, write
and
. Then
, so the common factor repeats the
parametrization. Flores-Córdova et al. (2026) use
,
,
, and
. Their actual antenna is a polygonal wire constructed
from sampled points of the projected curve, rather than
the smooth projected curve itself.
In the complex torus usage, the defining lattice is square,
|
(13)
|
where
is a complex number, and the quotient
space
has half-period ratio
. Its Weierstrass
elliptic function has invariants
and
, giving the lemniscate
case. The normalized Klein's absolute
invariant is
,
whereas the usual j-function has
. An equivalent elliptic
curve, completed by its point at infinity,
is
|
(14)
|
This usage specifies a complex structure and does not select an embedding as a particular surface of revolution in three-dimensional space (Cecotti and Vafa 2013, Appendix B.3; Eremenko 2023).
Zavizion (2006) uses the name for a homogeneous solid of revolution bounded by rotating a Bernoulli lemniscate
about its symmetry axis in a study of gravitational fields. Its meridian
is a lemniscate, and its boundary is the limit of the geometric family above,
|
(15)
|
It has a singular point at the origin. The
family has an open central hole.