# RuntimeWarning: Invalid value encoutered in sqrt

**URL:** <https://pyfr.discourse.group/t/runtimewarning-invalid-value-encoutered-in-sqrt/793>\
**Category:** Errors\
**Created:** [11 April 2023 05:42 UTC](https://pyfr.discourse.group/t/runtimewarning-invalid-value-encoutered-in-sqrt/793 "2023-04-11T05:42:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Yujif1Aero](https://yyz2.discourse-cdn.com/free1/user_avatar/pyfr.discourse.group/yujif1aero/32/448_2.png) [@Yujif1Aero](https://pyfr.discourse.group/u/Yujif1Aero)\
**Post date:** [11 April 2023 05:42 UTC](https://pyfr.discourse.group/t/runtimewarning-invalid-value-encoutered-in-sqrt/793/1 "2023-04-11T05:42:03Z")

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Dear all,

I have come across invalid value encountered in sqrt which I cannot solve.  
Could you teach me what wrong is?

Thank you

 ![image](https://global.discourse-cdn.com/free1/uploads/pyfr/original/1X/bf62c61649200f547c9c3d4faf11fbe134584b20.png)

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<div class="post-metadata">

**Author:** ![WillT](https://avatars.discourse-cdn.com/v4/letter/w/bc79bd/32.png) [@WillT](https://pyfr.discourse.group/u/WillT)\
**Post date:** [11 April 2023 07:53 UTC](https://pyfr.discourse.group/t/runtimewarning-invalid-value-encoutered-in-sqrt/793/2 "2023-04-11T07:53:08Z")

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This is most likely due to a negative or NaN value being passed to square root. What this probably means is that your simulation has diverged and another plugin was called before the Nan checker.