Parametric plot where [math]x(t)[/math] and [math]y(t)[/math] are the two [i]Fresnel functions[/i]. The resulting curve is called the [i]Euler spiral[/i] (see [url]http://en.wikipedia.org/wiki/Fresnel_integral[/url]). I've set the point [math]P(x_t, y_t)[/math] to run through the colours of the rainbow as a function of [math]t[/math] just to help us see the point when it's spiralling tightly. Also, it's pretty.