# Error while loop on Eigenvalue Problem

**URL:** <https://community.freefem.org/t/error-while-loop-on-eigenvalue-problem/1939>\
**Category:** General Discussion\
**Created:** [August 11, 2022, 4:28pm UTC](https://community.freefem.org/t/error-while-loop-on-eigenvalue-problem/1939 "2022-08-11T16:28:45Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Carina](https://avatars.discourse-cdn.com/v4/letter/c/8baadc/32.png) [@Carina](https://community.freefem.org/u/Carina)\
**Post date:** [August 11, 2022, 4:28pm UTC](https://community.freefem.org/t/error-while-loop-on-eigenvalue-problem/1939/1 "2022-08-11T16:28:45Z")

</div>

Hi there,  
I try to solve a Eigenvalue problem on a loop with coarser mesh on each step. It works perfectly fine with the Element “P1nc”, but when I use the Element “P3” for example, I get the error

> current line = 37  
> Exec error : arpack error NO\_SHIFTS\_APPLIED [sd]aupp  
> – number :3  
> Exec error : arpack error NO\_SHIFTS\_APPLIED [sd]aupp  
> – number :3  
> err code 8 , mpirank 0

Does anyone know why and how I can fix it?

This is the file:  
[testest.edp](https://community.freefem.org/uploads/short-url/tLDwHIrSIyPq7clKCeZyHhnrBUs.edp) (1.2 KB)

---

<div class="post-metadata">

**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:** [August 12, 2022, 11:38am UTC](https://community.freefem.org/t/error-while-loop-on-eigenvalue-problem/1939/2 "2022-08-12T11:38:31Z")

</div>

This error is very strange it occurs only in P3 element.

to remove  
start up loop a 2 no 1

```auto
 int n = 10;
 for (int m=2; m<=n; m++){

```