William Stein wrote:
> On Tue, Oct 14, 2008 at 8:07 AM, Marshall Hampton <[EMAIL PROTECTED]> wrote:
>> I am trying to do a demo for a class and I have encountered a strange
>> and very annoying error (or I am missing something).
>>
>> If I do:
>> {{{
>> var('x,y')
>> f = (x^2+y^2)^(.5)
>> cp = contour_plot(f,(-3,3),(-4,4), fill=False, plot_points = 80, cmap
>> = 'winter', contours=srange(2.9,3.1,.1))
>> g = x^2/4+y^2/9-1
>> gp = implicit_plot(g,(-3,3),(-4,4), plot_points = 80)
>> pts = point2d([[0,3],[2,0],[-2,0],[0,-3]])
>> show(cp+gp+pts,figsize = [7*3/4,7])
>> }}}
>> then the points with positive coordinates seem misplaced by about 1/10
>> of a unit; they should be on the ellipse.
>>
>> -M. Hampton
>
> If you replace 80 by 500 above then everything looks fine.
You took the words right out of my mouth. However, that implicit plot
comes up as a black ellipse for me (3.1.2 and 3.1.3rc0). I don't think
it should be filled, though, as it should be a plot of x^2/4+y^2/9==1,
not <=1. Is anyone else seeing that problem?
Jason
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