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parametric_plot3d throws an error when the sum of the components cancels a variable #2858
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comment:1
This is a duplicate of #1877. I think it should be possible to use a variable mutliple times in the range, i.e. Jason: feel free to reopen if you disagree. Cheers, Michael |
comment:2
To my understanding, the issue in #1877 was the specifying of the same variable in two different ranges. This issue is different: when I use "-u", I get an error, but when I use an expression that is equivalent to "-u", I don't get an error. In either case, I'm not specifying two of the same variable for the ranges. I think these issues are different. They may be symptoms of the same thing, but I doubt it. |
comment:4
Changing the issue title to be more descriptive. To elaborate on the reopening: the issue here is not with the ranges (to my knowledge, it isn't even possible to specify variables for the ranges in parametric_plot3d). The issue here is with the components of the function being plotted. |
comment:5
Ok, agreed that this is a different bug than #1877:
Using u twice in the range might have obscured the real bug from my POV. Mea culpa. +1 on the better description. Cheers, Michael |
comment:6
The problem seems to be in parametric_plot3d.py in adapt_to_callable, in the line "s=sum(f)". If there is a u and a -u as components of f, then sum(f) cancels these and the variable disappears. |
Attachment: trac_2858.patch.gz mike found one bug which this fixes. |
comment:8
Attachment: trac_2858-part2.patch.gz |
comment:9
Looks good to me. |
comment:10
Merged both patches in Sage 3.3.alpha3 |
The following two plots should give the same thing.
Component: graphics
Issue created by migration from https://trac.sagemath.org/ticket/2858
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