# Periodic BC with DG spaces

**URL:** <https://community.freefem.org/t/periodic-bc-with-dg-spaces/3100>\
**Category:** General Discussion\
**Created:** [April 14, 2024, 4:12pm UTC](https://community.freefem.org/t/periodic-bc-with-dg-spaces/3100 "2024-04-14T16:12:28Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![amirmahdimech](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@amirmahdimech](https://community.freefem.org/u/amirmahdimech)\
**Post date:** [April 14, 2024, 4:12pm UTC](https://community.freefem.org/t/periodic-bc-with-dg-spaces/3100/1 "2024-04-14T16:12:28Z")

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Is it possible to implement bi-periodic condition for solving a pde on a 1 by 1 square which is discretized by H(div),RT space functions in freeFEM?

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**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:** [April 16, 2024, 2:50pm UTC](https://community.freefem.org/t/periodic-bc-with-dg-spaces/3100/2 "2024-04-16T14:50:22Z")

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Yes, but I never try.

mesh Th=square(50,50);  
fespace Vh(Th,RT0,periodic=[[1,x],[3,x],[2,y],[4,y]]);

Vh [u1,u2]=[sin(x_2_pi),cos(y_2_pi)];  
plot([u1,u2],wait=1);