[Maxima] Can't escape from sign question loop

[Raymond Toy (RT/EUS)]

Robert Dodier wrote:
> 
> (3) plot2d is very optimistic --- it keeps trying different values
> in the range of the variable over which to plot, even if the
> expression doesn't return a number. (It is a loop within plot2d
> which causes all the asksign questions; it is not that Maxima
> is stuck within asksign itself.) Maybe plot2d shouldn't try so hard.

This is due to the adaptive plotter and the lack of a way for maxima to 
tell if the result is a number or not.  The plotter needs some way to 
know if we're at some kind of undefined point, and throw out of 
plotting.  But we don't want to quit completely because we might be able 
to plot over a sub region of the desired region.

Not sure what to do.

Ray