2-D comet plot
comet(y) displays a comet graph of the vector y. A comet graph is an animated graph in which a circle (the comet head) traces the data points on the screen. The comet body is a trailing segment that follows the head. The tail is a solid line that traces the entire function.
comet(axes_handle,...) plots into the axes with the handle axes_handle instead of into the current axes (gca).