Butterfly Curve

Parametric curves

Temple Fay’s 1989 transcendental curve whose sine and exponential terms flutter into a butterfly.

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Equation

x=sint(ecost2cos4tsin5t12)x = \sin t\left(e^{\cos t} - 2\cos 4t - \sin^5\tfrac{t}{12}\right)
y=cost(ecost2cos4tsin5t12)y = \cos t\left(e^{\cos t} - 2\cos 4t - \sin^5\tfrac{t}{12}\right)

Open the Creator with a ready-made animation brief for this curve — review the scene plan and Manim code before rendering.

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What is the Butterfly Curve?

The butterfly curve was published by Temple H. Fay in 1989 as a showcase of how rich a single polar-style formula can be. The radius e^{cos t} − 2cos 4t − sin⁵(t/12) mixes three rhythms: a slow exponential breathing, a four-fold wing beat from cos 4t, and a very slow sin⁵(t/12) drift with period 24π that keeps each pass slightly different.

Because of that slow drift, the curve does not repeat until t has swept 24π — twelve full turns — layering wing inside wing. It has become a standard test piece for plotting software and a favorite “wow” example in parametric-equation lessons.

Key properties

  • Transcendental (not algebraic): the exponential term rules out any polynomial equation.
  • Full period is 24π, set by the sin⁵(t/12) term.
  • Symmetric about the y-axis (swapping t → −t mirrors x).
  • Radius stays within e + 3 of the origin, bounding the wingspan.
  • A polar variant r = e^{sin θ} − 2cos 4θ + sin⁵((2θ − π)/24) draws a cousin butterfly.

Where you'll see it

Plotting-software demos, parametric equation showpieces, generative art, and laser projection tests.