On Oct 14, 9:45 am, Jason Grout <jason-s...@creativetrax.com> wrote:
> kcrisman wrote:
>
> > On Oct 13, 10:44 pm, Jason Grout <jason-s...@creativetrax.com> wrote:
> >> kcrisman wrote:
>
> >>> On Oct 13, 6:05 pm, "ma...@mendelu.cz" <ma...@mendelu.cz> wrote:
> >>>> Hello all, is there any other possibility how to plot implicit
> >>>> function than implicitplot?
> >>>> I do not like implicitplot too much, since it is in fact countourplot
> >>>> and it is not easy to set the color (for example).
> >>> There is not currently any other way to do this, I think. A colleague
> >>> of mine has some experimental code to implicit plot the "right" way
> >>> (by following derivatives around and spot-checking nearby to not miss
> >>> components, I guess), but doesn't consider it ready for prime time
> >>> yet.
> >> How do you do an implicit plot "right"? Scipy has tools for numerical
> >> integration (you mention following derivatives), if that helps.
>
> >> A quick google search turns up several references to
> >> software:http://geomblog.blogspot.com/2008/01/plotting-implicit-functions-bleg...
>
> >> The maple help page may
> >> help:http://www.maplesoft.com/support/help/Maple/view.aspx?path=plots/impl...
>
> >> This issue has come up before on the list (and Josh Kantor gave an
> >> algorithm and a
> >> reference):https://groups.google.com/group/sage-devel/browse_thread/thread/6b1d3...
>
> >> More references and
> >> algorithms:http://www.tangentspace.net/cz/archives/2007/08/implicit-plotting-cod...
>
> >> Mma also says: ContourPlot initially evaluates f at a grid of equally
> >> spaced sample points specified by PlotPoints. Then it uses an adaptive
> >> algorithm to subdivide at most MaxRecursion times to generate smooth
> >> contours.http://reference.wolfram.com/mathematica/ref/ContourPlot.html
>
> > Yes to all the above.
>
> I guess we can do a "better" job than matplotlib, as matplotlib does not
> have the function to go off of. In a sense, then, you are describing an
> adaptive evaluation of the function (at least, that's how mma seems to
> do it). I wonder if matplotlib can draw a contour plot from a
> non-rectangular grid.
>
> This sounds like an excellent project for a calc 3 student!
>
> Jason
>
This is now #7211.
- kcrisman
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