Gaston Julia (1893–1978), a French mathematician, studied the iteration of polynomials and rational functions in the early 20th century. A strikingly beautiful picture is produced from function iterations: a, f(a), f(f(a)), f(f(f(a))), etc. Mandelbrot sets, named after mathematician Benoit B. Mandelbrot (1924–), are whole families of functions parameterized by a variable. These sets have become something of an art form.