Re: [Maxima-discuss] Fun example of the adaptive plot routine

[Robert D. <rob...@gm...>]

On Thu, Jun 8, 2023 at 6:08 AM Gunter Königsmann via Maxima-discuss
<max...@li...> wrote:

> Not a bug - and arguably not even avoidable. But this week I found a fun example of the adaptive plot routine creating an alias effect:
>
> draw2d(
>     explicit(sin(x*81),x,1,10)
> )$

Haha, that's a good one. Here's a way to have some more fun with it.
Capture the points at which sin is evaluated and then plot those along
with a smoother (greater nticks) version.

foo(x):=block([y:sin(x*81)], push ([x,y],L), y);
L: [];
plot2d(foo,[x,1,10]); /* shows a straight line */
plot2d ([sin(x*81), [discrete, L]], [x, 1, 10], [nticks, 87], [style,
lines, points]);

Now the line plot shows the sine waves as expected, overlaid with the
points from before. Zooming in on the plot shows how the points fall
on successive waves.

I suspect any adaptive plotting routine can be fooled -- I don't feel
much motivation to modify Maxima's existing adaptive plotter, although
we might consider increasing the default value of nticks.

best

Robert