On Tue, Dec 8, 2015 at 12:38 PM, Ursula Whitcher <whitc...@uwec.edu> wrote:
> In Sage's contour plots, the default colors shade from black to white. This
> applies to both the shades used to fill and the actual color of the contour
> lines. If you turn off the fill color, the highest contour will be
> white-on-white, and thus invisible. Here's an example (notice the label
> floating apparently in the middle of nowhere):
>
> x,y = var('x,y')
> pl = contour_plot(-10*(x^2+y^2), (x,-1,1), (y,-1,1), fill = False, labels =
> True, label_fontsize = 13).show()
>
> You can fix this by making all the contour lines black. The keyword
> cmap=[(0,0,0)] worked for me.
>
> Can we change the defaults so that fill=False does not default to
> white-on-white? Or add a keyword that will make all contour lines the same
> color? Or at least add an example about this to the documentation?
>
What does Mathematica do?
https://reference.wolfram.com/language/ref/ContourPlot.html
Originally when implementing Sage graphics, we tried to very roughly
look at what Mathematica does (regarding their public API), and only
diverge from it when we could do something better (e.g., adding
graphics to superimpose them, which is pythonic). This makes it
easier to switch back (and forth) between Sage and Mathematica. Of
course, many people involved in Sage graphics have never used
Mathematica and didn't even know that Mathematica inspired some of our
design.
-- William
> --Ursula.
>
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William (http://wstein.org)
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