# Unable to extract eigenpair from SLEPc eigenvalue solver

**URL:** <https://fenicsproject.discourse.group/t/unable-to-extract-eigenpair-from-slepc-eigenvalue-solver/7435>\
**Category:** Uncategorized\
**Created:** [January 8, 2022, 6:05pm UTC](https://fenicsproject.discourse.group/t/unable-to-extract-eigenpair-from-slepc-eigenvalue-solver/7435 "2022-01-08T18:05:39Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Shubham\_Saurabh](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/shubham_saurabh/32/3460_2.png) [@Shubham\_Saurabh](https://fenicsproject.discourse.group/u/Shubham_Saurabh)\
**Post date:** [January 8, 2022, 6:05pm UTC](https://fenicsproject.discourse.group/t/unable-to-extract-eigenpair-from-slepc-eigenvalue-solver/7435/1 "2022-01-08T18:05:39Z")

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Hi all, I am trying to compute eigen values and eigen vectors using SLEPc eigenvalue solver for a large degrees of freedom system(more than one million). There are cylindrical holes in it where I have assigned some external point masses. I have assembled them in K(stiffness) and M(mass) matrices. While using `SLEPc eigenvalue solver`, I am getting error- `Unable to extract eigenpair from SLEPc eigenvalue solver`. The reason is given- `Requested eigenpair (0) has not been computed`.

 ![Screenshot 2022-01-08 232635](https://global.discourse-cdn.com/free1/uploads/fenicsproject1/original/2X/5/5190912bad4f7063076f64ff85ba4dd63b8cf107.png)

Can you please tell the possible reason and its solution.