various plot2d issues



On 4/4/07, Stavros Macrakis <macrakis at alum.mit.edu> wrote:

>      plot2d([discrete,makelist([i/10.0,ff(i/10.0)],i,0,30)]),
>
> which should be roughly equivalent (with closer control of plotted
> points) gives an internal error, complaining that UND is not (or
> rational lisp:float).

plot2d([discrete, ...]) should probably just exclude any nonnumeric points.

> When Y-limiting, plot2d *ignores* points outside the y-limits rather
> than drawing the line and clipping it at the Y-limit.  Thus
> plot2d(sin(x),[x,0,3],[y,0,.5]) has gaps between the plotted lines and
> the top of the graph.

Yeah, that doesn't look good. Maybe the logic should be changed
to something like: if point is out of bounds but point to the immediate
left or right is in-bounds, then output the point anyway.

> plot2d doesn't understand INF.

Dunno what we can do here. Maybe Maxima should substitute
a huge floating point value for inf (likewise minf) and then hope
the plotting package can do something useful with it.

FWIW
Robert

PS. I hope someone is keeping a wish list or something ....