residue complex number by matlab
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how can I find the residue of (z+1)/(z^3 (z-2)) by using matlab ?
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John D'Errico
2015년 3월 13일
I can't recall if I ever published this tool. I thought I did.
fun = @(z) (z+1)./(z.^3.*(z-2));
format long g
We know z=2 to be a first order pole.
[res,err] = residueEst(fun,2,'poleorder',1)
res =
0.375
err =
8.8624722305483e-16
And z=0 is a 3rd order pole.
[res,err] = residueEst(fun,0,'poleorder',3)
res =
-0.187500006276744
err =
2.93992309142077e-09
Expect a wee bit less accuracy around higher order poles, but it still did reasonably well.
As I said, I thought it was posted on the File Exchange, but it may not have been. I've written so many neat toys over the years, that sometimes I forget to post them...
As it turns out, I never did post it. I'll update the limest submission to include residueEst, as they are both limit calculators.
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John D'Errico
2015년 3월 16일
That is good to know. Too often these tools contain nice additional abilities that we old-timers never realize were added.
Niklas Kurz
2021년 7월 15일
편집: Niklas Kurz
2021년 7월 15일
what if there is an indetermined variable in the function? (fun = @(z,a)). Can it deal with two parameters?
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