# How to deal with the boundary conditions of 1D discontinuous finite element?

**URL:** <https://community.freefem.org/t/how-to-deal-with-the-boundary-conditions-of-1d-discontinuous-finite-element/1871>\
**Category:** General Discussion\
**Created:** [July 3, 2022, 11:58am UTC](https://community.freefem.org/t/how-to-deal-with-the-boundary-conditions-of-1d-discontinuous-finite-element/1871 "2022-07-03T11:58:56Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Qianrui](https://avatars.discourse-cdn.com/v4/letter/q/9fc348/32.png) [@Qianrui](https://community.freefem.org/u/Qianrui)\
**Post date:** [July 3, 2022, 11:58am UTC](https://community.freefem.org/t/how-to-deal-with-the-boundary-conditions-of-1d-discontinuous-finite-element/1871/1 "2022-07-03T11:58:56Z")

</div>

How to deal with the boundary conditions of 1D discontinuous finite element?

problem KDV(u1,v)=int1d(Thf)(u1_v/dt)-int1d(Thf)(u0_v/dt)  
+int1d(Thf)(dx(u1)\*dxx(v))  
-intallBE(Thf)(jump(dxx(u1)_v)  
-intallBE(Thf)(jump(dx(u1)dx(v))  
-int1d(Thf)(u0u1_dx(v));  
//error faild  
-intallBE(Thf)(jump(dxx(u1)\*v) error operator ( \<10LinearCombISt4pairI7MGauche6MDroitE4C\_F0E\>  
List of choices  
( \<10LinearCombI6MDroit4C\_F0E\> : \<10LinearCombI6MDroit4C\_F0E\> )  
( : )  
( : )  
( \<10LinearCombI7MGauche4C\_F0E\> : \<10LinearCombI7MGauche4C\_F0E\> )