# ICCG with accleration in PETSc

**URL:** <https://community.freefem.org/t/iccg-with-accleration-in-petsc/2865>\
**Category:** General Discussion\
**Created:** [January 5, 2024, 4:06pm UTC](https://community.freefem.org/t/iccg-with-accleration-in-petsc/2865 "2024-01-05T16:06:46Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![ksugahar](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/ksugahar/32/2115_2.png) [@ksugahar](https://community.freefem.org/u/ksugahar)\
**Post date:** [January 5, 2024, 4:06pm UTC](https://community.freefem.org/t/iccg-with-accleration-in-petsc/2865/1 "2024-01-05T16:06:46Z")

</div>

I am trying to solve my problem by ICCG with an acceleration factor.

The method itself is described in the following article.

> **[ToM48-2\_519-522.pdf](https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/48513/1/ToM48-2_519-522.pdf)**
>
> 463.44 KB

I am trying to find a way to do the acceleraion with PETSc, but so far I have not found a way to do it. I have generated a plugin module to do it, but if it can be done with PETSc, it is better. Does anyone have idea?

---

<div class="post-metadata">

**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [January 6, 2024, 6:26am UTC](https://community.freefem.org/t/iccg-with-accleration-in-petsc/2865/2 "2024-01-06T06:26:59Z")

</div>

Incomplete Cholesky factorization is one of the worst preconditioner available, but you can just do `-ksp_type cg -pc_type icc`.