# Jump boundary condition (discontinous galerkin)
**URL:** https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073
**Category:** General Discussion
**Created:** [October 19, 2022, 9:07am UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073 "2022-10-19T09:07:21Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@RodZ](https://community.freefem.org/u/RodZ)
#### Post date: [October 19, 2022, 9:07am UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073/1 "2022-10-19T09:07:21Z")
Hi everyone,
I would like to implement the following variational problem:
\begin{cases} -div(A\_i \nabla u\_i) = f \text{ in } \Omega\_i \\ (A\_1 \nabla u\_1) \cdot n = (A\_2 \nabla u\_2) \cdot n \text{ on } \Gamma = \partial \Omega\_1 \cap \partial \Omega\_2 \\ (A\_1 \nabla u\_1) \cdot n = \alpha(u\_2 - u\_1) = \alpha[u] \text{ on } \Gamma = \partial \Omega\_1 \cap \partial \Omega\_2 \\ Ai \nabla u\_i = 0 \text{ on } \Gamma\_N \\ u = g\_D \text{ on } \Gamma\_D \end{cases}
The variational formulation is in a broken sobolev space (due to the discontinuity at \Gamma):
\int\_{\Omega\_1}A\_1 \nabla u\_1 \cdot \nabla v\_1 dx + \int\_{\Omega\_2}A\_2 \nabla u\_2 \cdot \nabla v\_2 dx + \int\_\Gamma \alpha [u][v] ds = 0
with u=g\_D \text{ on } \Gamma\_D
Is it possible to to this in FreeFEM? in particular for the jump on the boundary condition at the interface \Gamma. I know that in FreeFEM it exists the discontinuous galerkin, but when i tried to do this, it says me the following error:
> Error umpfack umfpack\_di\_numeric status 1
> Error umfpack\_di\_solve status 1
Merci bcp,
Rodrigo
---
### Author:  [@frederichecht](https://community.freefem.org/u/frederichecht)
#### Post date: [October 19, 2022, 9:28am UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073/2 "2022-10-19T09:28:13Z")
Yes some year ago, I Mc Bain exactly this problem in freefem day 2012
> **[McBain.pdf](https://www.ljll.fr/hecht/ftp/ff++days/2012/McBain.pdf)**
>
> 573.41 KB
I have do a exemple but it is not clean .
---
### Author:  [@RodZ](https://community.freefem.org/u/RodZ)
#### Post date: [October 19, 2022, 9:30am UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073/3 "2022-10-19T09:30:54Z")
Thank you very much, dear professor.
In order to understand, why intalledges(Th)(…) or intallBE(Th)(…)
doesn’t work if i’m using galerkin discontinous?
---
### Author:  [@frederichecht](https://community.freefem.org/u/frederichecht)
#### Post date: [October 19, 2022, 9:45am UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073/4 "2022-10-19T09:45:43Z")
If you use DG , it is a other story, it possible but I have no time to explain.
---
### Author:  [@YangChe98](https://community.freefem.org/u/YangChe98)
#### Post date: [October 23, 2024, 12:52pm UTC](https://community.freefem.org/t/jump-boundary-condition-discontinous-galerkin/2073/5 "2024-10-23T12:52:40Z")
The file seems to be inaccessible. Could you kindly re-upload it when you have a moment? Thank you!