Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The butterfly curve is a transcendental plane curve discovered by Temple H. Fay. n mathematics, a plane curve is a curve in a Euclidian plane (cf. space curve). The most frequently studied cases are smooth plane curves (including piecewise smooth plane curves), and algebraic plane curves. A smooth plane curve is a curve in a real Euclidian plane R2 and is a one-dimensional smooth manifold. Equivalently, a smooth plane curve can be given locally by an equation (x,y) = 0, where : R2 R is a smooth function, and the partial derivatives / x and / y are never both 0. In other words, a smooth plane curve is a plane curve which "locally looks like a line" with respect to a smooth change of coordinates.