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Error rendering 3d scene

asked 2015-09-20 07:03:28 -0500

Jeremy Martin gravatar image

I'm working in the SageMath Cloud. The code block

x,y,t = var('x,y,t')
f = lambda x,y: x*abs(y)/sqrt(x^2+y^2) if (x,y)<>(0,0) else 0
a,b = 1,6
e = 0.1
parametric_plot3d( [b*t, -a*t, f(b*t,-a*t)], [t,-e,e], color="yellow", size=15 )

produces an error message:

error rendering 3d scene -- error downloading /blobs/682b952d-d577-45ce-98ff-4e7a06ddad32.sage3d?uuid=682b952d-d577-45ce-98ff-4e7a06ddad32

But if I change the fourth line to e = 1, then it works just fine.

A similar error was reported in http://ask.sagemath.org/question/2730..., but the fix there was easier.

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Update: Having read http://ask.sagemath.org/question/2632..., I tried e = 1/10 and got the same error. Of course

parametric_plot3d( [b*t/e, -a*t/e, f(b*t/e,-a*t/e)], [t,-1,1], color="yellow", size=15 )

will do what I want, but there still seems to be an underlying problem with parametric_plot3d.

Jeremy Martin gravatar imageJeremy Martin ( 2015-09-20 07:04:44 -0500 )edit

I've tried my local sage installation and the sagecell and the code seems to work. I think this is an issue specific to the cloud. The threshold seems to be e=0.2.

fidbc gravatar imagefidbc ( 2015-09-20 21:35:41 -0500 )edit

Same here, i can not reproduce your error from a local install. You should contact sagemathcloud.

tmonteil gravatar imagetmonteil ( 2015-09-24 16:00:54 -0500 )edit

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answered 2016-01-12 14:20:44 -0500

William Stein gravatar image

updated 2016-01-13 11:54:54 -0500

kcrisman gravatar image

Your blob is too large. Explicitly set the number of plot_points to be smaller:

parametric_plot3d( [b*t, -a*t, f(b*t,-a*t)], [t,-e,e], color="yellow", size=15, plot_points=200 )

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Is that a bug, though, if SMC can't do what local and Sagecell can do?

kcrisman gravatar imagekcrisman ( 2016-01-13 11:54:40 -0500 )edit

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Asked: 2015-09-20 07:03:28 -0500

Seen: 509 times

Last updated: Jan 13 '16