数学图形(1.35)Kappa curve

不知道这个曲线和那个运动品牌背靠背有什么关系.阿迪原先的商标是个三叶草,难道背靠背也是由数学图形来的?

以下是维基上的解释.

In geometry, the kappa curve or Gutschoven's curve is a two-dimensional algebraic curve resembling the Greek letter ϰ (kappa). The kappa curve was first studied by Gérard van Gutschoven around 1662. In the history of mathematics, it is remembered as one of the first examples of Isaac Barrow's application of rudimentary calculus methods to determine the tangent of a curve. Isaac Newton and Johann Bernoulli continued the studies of this curve subsequently.

Using the Cartesian coordinate system it can be expressed as:

x^2(x^2 + y^2)=a^2y^2

#http://www.mathcurve.com/courbes2d/kappa/kappa.shtml

vertices = 

t = from  to (*PI)

r =
a = r*tan(t)

x = a*cos(t)
y = a*sin(t)

#http://www.mathcurve.com/courbes2d/kappa/kappa.shtml

vertices = 

t = from  to (*PI)

r =
a = r*tan(t)

x = a*sin(t)
y = a*cos(t)