Apart from just looking at this particular plot and trying to manage it,
look at the actual problem in depth. Please look at how plotting points are
evaluated. Even though Sage is capable of evaluating these points, it (or
matplotlib?) is evaluating y coordinates after 88 as inf or nan.
Please see my post above with one evaluation with
for T in srange(1,100,1.0):
and another with
for T in srange(1,100,1):
The difference is that the increment is a float. And also range(1,100,1)
produces the same result as srange(1,100,1).
Also,
> parametric_plot(C, (t,89.0,95.0))
clearly says that here the y values above 88 are evaluated as inf or nan
even though they are not and Sage is capable of evaluating them correctly.
What if these things creep into plotting ranges which we are really
interested in, where we expect y value to be a finite value but the program
calculates as inf or nan.
Here one thing to observe is that the vertical line is appearing
because after 88 the y value is wrongly calculated as inf or nan and the
plotter is turning them into 0 to handle it and hence the plot suddenly
falls to y=0 (x is not affected though).
*Regards*
*Niranjana*
On Thu, Jul 7, 2022 at 12:44 AM Samuel Lelievre <samuel.lelie...@gmail.com>
wrote:
> In case the hope in extending the range of t further and further
> was to capture the missing portion of the curve, it turns out
> the problem is at the other end, near zero.
>
> The curve is missing its initial segment, because
>
> - parametric_plot(C, (t, a, b)) uses equispaced evaluation points
> along the interval [a, b], skipping points where evaluation fails
> - C cannot be evaluated at zero
> - C travels quite some distance when t runs through (0, 0.01)
>
> To better view the curve, plot an initial arc separately,
> say for t in the interval (10^-9, 10^-2); then the rest of
> the curve, say up to t = 7.
> ```
> pa = parametric_plot(C, (t, 1e-9, 1e-2), color='steelblue')
> pb = parametric_plot(C, (t, 1e-2, 7), color='steelblue')
> p = pa + pb
> p.show()
> ```
>
> There is not much point plotting further than t = 7.
> Check how short the arc for t running along [7, 88] is:
> ```
> pc = parametric_plot(C, (t, 7, 88), color='firebrick')
> pc.show(xmin=-1.001, xmax=-0.999, ymin=0.495, ymax=0.505,
> aspect_ratio=1/10)
> ```
>
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