[Maxima-bugs] [maxima:bugs] #4595 residue bug

[Barton W. <wil...@us...>]

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**[bugs:#4595] residue bug**

**Status:** open
**Group:** None
**Labels:** residue 
**Created:** Thu Aug 14, 2025 03:18 PM UTC by Barton Willis
**Last Updated:** Thu Aug 14, 2025 03:18 PM UTC
**Owner:** nobody


Wrong
~~~
(%i4) residue(plog(x)/(x-%i*sin(%pi/9)-cos(%pi/9)),x,%e^((%i*%pi)/9));
(%o4) 0
~~~

OK, but should be more simple 
~~~
(%i5) residue(plog(x)/(x-%i*sin(%pi/9)-cos(%pi/9)),x,rectform(%e^((%i*%pi)/9)));
(%o5) (9*log(sin(%pi/9)^2+cos(%pi/9)^2)+2*%i*%pi)/18
~~~

Changing `plog` to `log` does not fix this problem.  

The testsuite sends this problem to `residue,` but I don't specifically know the test case that triggers this bug.

One possible fix is for the residue function to locally set  `taylor_simplifier` to `rectform`. 


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