Plot weight-bias position on error surface
H = plotep(W,B,E,H)
plotep is used to show network learning on a plot already created by plotes.
H= plotep(W,B,E) takes these arguments,
Current weight value
Current bias value
and returns a vector H, containing information for continuing the plot.
H = plotep(W,B,E,H) continues plotting using the vector H returned by the last call to plotep.
H contains handles to dots plotted on the error surface, so they can be deleted next time, as well as points on the error contour, so they can be connected.