[Maxima] nticks with explicit in draw package?

Andrej Vodopivec andrej.vodopivec at gmail.com
Wed Mar 12 12:58:48 CDT 2008


On Wed, Mar 12, 2008 at 6:52 PM, dlakelan <dlakelan at street-artists.org> wrote:
> Mario Rodriguez wrote:
>  > dlakelan escribió:
>  >> nticks doesn't seem to affect the workings of the explicit plot type in
>  >> draw, however the docs say that it does.
>  ...
>
> > Sorry, but the documentation doesn't reflect the real meaning of nticks,
>  > which is the same as in the plot-routine case. This is my fault, of course.
>
>  I have a function that takes a relatively long time to compute (it
>  involves doing a numerical integral inside a root finder, a typical
>  evaluation is about 2 seconds). When I plot it via plot2d or draw2d it
>  takes FOREVER. It appears that this is due to an interaction between the
>  adaptive plotting and the function. When the function changes rapidly,
>  it also takes longer to calculate the integral at each step, and the
>  plotting routine thinks it needs more points... So the adaptive plotting
>  routine basically zeros in on the MOST EXPENSIVE portion of the graph,
>  and decides to demand a lot of points there... At least that's what I
>  think is going on.
>
>  Would it be possible to create a variable that controls the max plot
>  time, so that the adaptive algorithm has a time budget that keeps it
>  from going off into neverland?
>
>  Just a thought. In the mean time I've converted to using parametric
>  plots with nticks=15, so that my plot completes in 20 seconds rather
>  than 30 minutes. Not as smooth, but acceptable.

Decreasing the value of adapt_depth might help with plot2d and
draw2d(explicit(...)).

-- 
Andrej



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