A swallowtail catastrophe is a catastrophe which can occur for three control factors and one behavior axis. The swallowtail catastrophe
is the universal unfolding of singularity with codimension 3, i.e., in three unfolding parameters,
and is of the form
.
The equations
|
(1)
| |||
|
(2)
| |||
|
(3)
|
display such a catastrophe (von Seggern 1993, Nordstrand). The above surface uses
and
.
After relabeling the coordinates as ,
the parametrization satisfies the implicit equation
|
(4)
|
The left side is the polynomial discriminant of
with respect to
.
Hauser calls the implicit surface the Taube surface,
whose German name means "dove." Its real zero set
also contains points absent from the real parametrized image, such as
, for which the quartic is
.