# Implementation of Dirichlet boundary condition when tgv=-1

**URL:** https://community.freefem.org/t/implementation-of-dirichlet-boundary-condition-when-tgv-1/113
**Category:** Feature Request
**Created:** [August 19, 2019, 6:51pm UTC](https://community.freefem.org/t/implementation-of-dirichlet-boundary-condition-when-tgv-1/113 "2019-08-19T18:51:01Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![fotios.kasolis](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fotios.kasolis/32/18_2.png) [@fotios.kasolis](https://community.freefem.org/u/fotios.kasolis)
#### Post date: [August 20, 2019, 5:12pm UTC](https://community.freefem.org/t/implementation-of-dirichlet-boundary-condition-when-tgv-1/113/2 "2019-08-20T17:12:37Z")

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Dear @arousta,

According to [About the functions LinearCG](https://community.freefem.org/t/about-the-functions-linearcg/54/8) a symmetric elimination is possible with `tgv=-2`, although I never tried myself, and it is not available for the rhs, as far as I remember. On the other hand, the implementation is not that hard; at [Exact Dirichlet BC](https://community.freefem.org/t/exact-dirichlet-bc/52) I have presented a naive implementation at the level of FreeFEM itself.

Regards,  
/Fotios Kasolis

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