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2012-01-16 08:33:58 -0600 marked best answer Contour Plots and Points

The point is there -- it's simply lurking behind the contour plot. Or, in matplotlib jargon (one of the plotting packages Sage uses is called matplotlib), it doesn't have a higher zorder. The zorder is the layer level, where the layers are drawn from lower to higher.

I can never remember what zorders different things default to, but it's usually easily changed manually:

var('x,y')
f(x,y)=sin(x)*cos(y)
G = contour_plot(f(x,y),(x,-3,3),(y,-3,3),contours=20,plot_points=100)
G += point((1,1), size=100,zorder=2)
G.show()

produces

image description

2012-01-16 03:03:36 -0600 answered a question Contour Plots and Points

Thanks.

Just to be certain, why does subsequently plotting a line without a zorder not put that line behind the contour plot as well?

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2012-01-15 14:39:31 -0600 asked a question Contour Plots and Points

Why can I not have a single point on a contour plot?

var('x,y')

f(x,y)=sin(x)*cos(y)

G = contour_plot(f(x,y),(x,-3,3),(y,-3,3),contours=20,plot_points=100)

G += point((1,1), size=100) 

G.show()

does not display the point. I can add a line (for example)

G += line(((1.5,1),(1.5,0)))

and that line shows up but not the point.

Thanks.

JT

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2011-08-19 04:36:30 -0600 answered a question vector calc

There are numerous worksheets scattered about that deal with multivariate calculus but I don't know of any organized collection--yet. This is something that is being considered and hopefully will be available next time you teach this course.

I have published a number of short worksheets at Mississippi College and you are welcome to give any of them a try. Some of these are being designed to work from within WeBWorK and so may not have very much of a descriptive component.