Timeline for Issue with ContourPlot
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Jul 25, 2019 at 16:20 | history | edited | Michael E2 | CC BY-SA 4.0 |
added 185 characters in body
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| Jul 25, 2019 at 15:55 | history | edited | Michael E2 | CC BY-SA 4.0 |
Responded to comment
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| Jul 25, 2019 at 4:44 | comment | added | JimB | Thanks. Mathematics is not my strong point. I'll look at it and what you wrote in the comment. | |
| Jul 25, 2019 at 4:41 | comment | added | Michael E2 |
@JimB The picture is not perfectly clear (to me), and the appearance of the roots k0[[2]], k0[[3]] may even both be spurious. But the roots are definitely there for the exact parameters I used. They are also stable under perturbations of the parameters {A -> 1/2 (1 + eA), B -> 1/100000 (1 + eB), z -> -237/100 (1 + ez), T -> 1/10 (1 + eT)} for eA, eB, ez, eT up to ±10^-3 (k0[[2]] is about $8 \times 10^{-8}$ above $(\pi-1)/2$). I think what is happening is that as T -> 0, both x0[[2]] and x0[[3]] approach $(\pi-1)/2$. But I suspect they are distinct roots for T > 0.
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| Jul 25, 2019 at 3:36 | comment | added | JimB |
My last numerical analysis class was 45 years ago so please bear with me. I'm thinking that a zero doesn't occur at k = k0[[2]]. k0[[2]] is essentially $\frac{1}{2} (\pi -1)$ (a point of discontinuity). This is what the following plot tells me: Show[Plot[eq[1, k, 1/10], {k, 1, 1.2}, PlotPoints -> 1000, PlotRange -> {{1.06, 1.08}, {-100, 1000}}, MaxRecursion -> 5, WorkingPrecision -> 100], ListPlot[{{{k0[[2]], 0}, {k0[[2]], 1000}}, {{k0[[3]], 0}, {k0[[3]], 1000}}}, Joined -> True, PlotStyle -> {Red, Green}, PlotLegends -> {"k0[[2]]", "k0[[3]]"}]].
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| Jul 25, 2019 at 1:50 | history | answered | Michael E2 | CC BY-SA 4.0 |