#6002: parametric_plot3d appears not to give the correct axes values
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Reporter: wcauchois | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-4.0
Component: graphics | Keywords:
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Alden Walker describes the bug in a sage-support thread:
> When I run:
> {{{parametric_plot( (cos(t), sqrt(2)*sin(t)) , (t,0,2*pi))}}}
> I get a nice 2d parametric plot, with the top of the ellipse clearly
> hitting close to 1.5 on the y-axis. When I run:
> {{{parametric_plot3d( (cos(t), 1 , sqrt(2)*sin(t)), (t,0,2*pi))}}}
> The top of the ellipse really looks like it's at z=1, and the whole
> thing looks a lot like a circle.
Even though the bounding box is reported to be `((-1.0, 1.0, -1.41293...),
(1.0, 1.0, 1.41293...))`, jmol labels the axes as (-1, 1), (-1, 1), and
(0, 2).
If we construct the curve manually:
{{{
var('t')
from sage.plot.plot import var_and_list_of_values
_, vals = var_and_list_of_values((0, 2*pi), 75)
w = []
for t in vals:
w.append(map(float, (cos(t), 1, sqrt(2)*sin(t))))
}}}
Then notice that while {{{line3d(w)}}} is still incorrect,
{{{line3d(w[0:43])}}} looks correct -- that is, plotting only part of the
graph eliminates the error somehow. Quite curious!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6002>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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