Kampyle of Eudoxus

The Kampyle of Eudoxus (Greek: καμπύλη [γραμμή], meaning simply "curved [line], curve") is a curve with a Cartesian equation of

${\displaystyle x^{4}=a^{2}(x^{2}+y^{2}),}$

from which the solution x = y = 0 is excluded.