# PETSC Exec error : Check BilinearOperator N M

**URL:** <https://community.freefem.org/t/petsc-exec-error-check-bilinearoperator-n-m/1797>\
**Category:** General Discussion\
**Created:** [June 4, 2022, 7:02am UTC](https://community.freefem.org/t/petsc-exec-error-check-bilinearoperator-n-m/1797 "2022-06-04T07:02:58Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [June 4, 2022, 7:02am UTC](https://community.freefem.org/t/petsc-exec-error-check-bilinearoperator-n-m/1797/1 "2022-06-04T07:02:58Z")

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Hello, teacher, what is the reason for this?

> – Square mesh : nb vertices =66049 , nb triangles = 131072 , nb boundary edges 1024  
> – Square mesh : nb vertices =1089 , nb triangles = 2048 , nb boundary edges 128  
> — partition of unity built (in 5.870000e-05)  
> — global numbering created (in 5.030000e-05)  
> — global CSR created (in 1.965000e-04)  
> — global numbering created (in 3.960001e-05)  
> — global CSR created (in 1.208000e-04)  
> — global numbering created (in 1.221500e-03)  
> — global CSR created (in 1.486000e-04)
> 
> - 1 2\*0 0  
> current line = 64 mpirank 0 / 1  
> Exec error : Check BilinearOperator N M  
> – number :1  
> Exec error : Check BilinearOperator N M  
> – number :1  
> err code 8 , mpirank 0

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**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [June 4, 2022, 9:03am UTC](https://community.freefem.org/t/petsc-exec-error-check-bilinearoperator-n-m/1797/2 "2022-06-04T09:03:59Z")

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Please share a minimal running example.