When the graphing window is adjusted, why do implicitly defined graphs disappear, or appear in fragments?
Implicitly defined graphs are drawn by a special method, which establishes an anchor point (found by a random search) on each connected component of the graph (a complete display might consist of several components). If the view is adjusted (by zooming in, for example), it may happen that an anchor point is no longer visible, and the corresponding component will disappear. Curves that leave the view frame are usually clipped at the boundary. Because the program also preserves these clip points, they can become conspicuous if the view is adjusted (by zooming out, for example). If the View menu item Implicit redraw is checked, however, any window change will put the program back into search mode (forcing the recalculation of anchor and clip points), and implicit graphs should refresh normally.
