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)
| |||
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(2)
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The plane curve satisfies the Bernoulli lemniscate
equation
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(3)
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where
is the half-width and the distance from the center to either focus
is
. Rotating the curve
about the z-axis
gives
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(4)
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(5)
| |||
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(6)
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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
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(7)
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In cylindrical coordinates, with , a meridian
is parametrized by
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(8)
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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)
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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
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(10)
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where
and
are positive integers and
. Its orthogonal
projection onto the
-plane has the complex
number representation
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(11)
|
and satisfies
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(12)
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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,
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(13)
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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
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(14)
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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,
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(15)
|
It has a singular point at the origin. The
family has an open central hole.