# Getting flipped eigen values

**URL:** <https://community.freefem.org/t/getting-flipped-eigen-values/2994>\
**Category:** General Discussion\
**Created:** [February 24, 2024, 2:34am UTC](https://community.freefem.org/t/getting-flipped-eigen-values/2994 "2024-02-24T02:34:21Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Amitkaush](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/amitkaush/32/1978_2.png) [@Amitkaush](https://community.freefem.org/u/Amitkaush)\
**Post date:** [February 24, 2024, 2:34am UTC](https://community.freefem.org/t/getting-flipped-eigen-values/2994/1 "2024-02-24T02:34:21Z")

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when i tried for the simpler case of plane Poiseuille flow stability with Alpha=0,beta=1;  
instead of getting this eigen spectrum:  
 ![Screenshot 2024-02-24 080049](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/c/cf047ba2367b5640aaeac870039fae77857122c1.png)  
i am getting this:

 ![eigopp](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/a/a0eb061052ef2f977e82c7b8245be12a3f2310b7.png)  
That is real and imaginary parts are flipped.  
what can be the possible reason for this.

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**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [February 25, 2024, 8:50am UTC](https://community.freefem.org/t/getting-flipped-eigen-values/2994/2 "2024-02-25T08:50:23Z")

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With no script and theory no way.