Does anybody know the problem?
why is the plot hatched ? I just want a simple plot.
g[z_, t_] := 1 + t*z + z^3
Plot[Residue[1/(1 + t*z + z^3), {z, Root[Function[z, g[z, t]], 1]}], {t, 0, 10}]
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1$\begingroup$ Please show us the code text as you've done in your first question, rather than posting a screenshot. $\endgroup$– xzczdMar 17, 2020 at 8:56
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$\begingroup$ @Dear xzczd, my original problem is about polynomials of degree 4 which coefficient are functions of temperature as like as screenshot which have mentioned above. I want to plot T-dependence of roots and residue of them. sorry for posting many screenshots $\endgroup$– ArianMar 17, 2020 at 9:15
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$\begingroup$ I mean, please post the code text instead of the screenshot. Currently we'll have to transcribe the code from your screenshot if we want to test it. $\endgroup$– xzczdMar 17, 2020 at 9:24
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$\begingroup$ @xzczd thank you so much, yes, you are right, I should have sent code instead of it's screenshoot $\endgroup$– ArianMar 17, 2020 at 9:39
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$\begingroup$ -1×2, will retract my downvotes as soon as the code text are added to the questions. $\endgroup$– xzczdMar 17, 2020 at 9:58
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1 Answer
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Root cann't handel the additional parameter t!
Try
g[z_, t_] := 1 + t z + z^3
root[t_] := Root[Function[z, g[z, t]], 1]
Plot[Evaluate[Residue[1/g[z, t], {z, root[t] }]], {t, 0, 10} ]
answered Mar 17, 2020 at 9:33
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$\begingroup$ @Dear Ulrich Neumann, thank you so much, it was very clear. $\endgroup$– ArianMar 17, 2020 at 9:42
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$\begingroup$ The solution works, but the explanation is incorrect. This is a matter of precision. Try
Plot[Residue[1/g[z, t], {z, Root[Function[z, g[z, t]], 1] }], {t, 0, 10},WorkingPrecision->16 ]. $\endgroup$– xzczdMar 17, 2020 at 10:06 -
$\begingroup$ @xzcd Thanks for your clarification. Nevertheless in my opinion a numerical solution which doesn't need high workingprecision is quite reliable. $\endgroup$ Mar 17, 2020 at 10:40
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$\begingroup$ That's true, your solution is the better choice for resolving the problem. $\endgroup$– xzczdMar 17, 2020 at 11:17