# About intalledges and internal edges

**URL:** <https://community.freefem.org/t/about-intalledges-and-internal-edges/3231>\
**Category:** General Discussion\
**Created:** [May 8, 2024, 3:17pm UTC](https://community.freefem.org/t/about-intalledges-and-internal-edges/3231 "2024-05-08T15:17:19Z")\
**Posts on this page:** 1\
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**Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\
**Post date:** [May 9, 2024, 11:14am UTC](https://community.freefem.org/t/about-intalledges-and-internal-edges/3231/2 "2024-05-09T11:14:47Z")

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You have a quantity named `nTonEdge` assciated to each edge, that contains the number of triangles touching the edge. Its value is thus 2 for internal edge, and 1 for boundary edge.  
You can just then mutiply your expression in `intalledges` by `(nTonEdge-1)`, this will give zero for the boundary terms, and 1 for internal terms. For example  
`+intalledges(Th)(mean(u)*jump(v)*(nTonEdge-1))`

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