The definition of the Mandelbrot set is based on the mapping . This Demonstration uses a variation of the mapping, , where is the Weierstrass function, , , and are real, and is complex. The escape radius is , the initial value is (restricted to be in a region), and the function is computed at resolution .
 J. Hawkins, L. Koss, and M. Taylor. "Julia Sets of Weierstrass Elliptic P functions with Toral Band Fatou Components," linked from Graphics Images of Julia Sets of Nonpolynomial Maps. (Nov 11, 2014) www.unc.edu/math/Faculty/jhawkins/graphics.html.