# Edge03d Finite Element Assembly

**URL:** https://community.freefem.org/t/edge03d-finite-element-assembly/600
**Category:** General Discussion
**Created:** [October 5, 2020, 7:22pm UTC](https://community.freefem.org/t/edge03d-finite-element-assembly/600 "2020-10-05T19:22:30Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![novelnj](https://avatars.discourse-cdn.com/v4/letter/n/48db29/32.png) [@novelnj](https://community.freefem.org/u/novelnj)
#### Post date: [October 5, 2020, 7:22pm UTC](https://community.freefem.org/t/edge03d-finite-element-assembly/600/1 "2020-10-05T19:22:30Z")

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Hello,

I am solving a electromagnetic numerical problem. I can construct the 3d Nedelec finite element with degree 1 (Edge03d) and the system matrix K. What I want to know is how the matrix K is been constructed in this case, especially how to assemble such global matrices.  
I can find the paper discussing higher-order Nedelec element online, which is HIGH ORDER EDGE ELEMENTS ON SIMPLICIAL MESHES. Is there any good reference that FreeFEM++ implements for the Nedelec element of degree 1?

Regards  
Botian Zhang

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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: [October 6, 2020, 2:47pm UTC](https://community.freefem.org/t/edge03d-finite-element-assembly/600/2 "2020-10-06T14:47:06Z")

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remark, for Edge03 the basic function are

just ± ( grad(Ni)Nj - grad(Nj)Ni) on edge (i,j) where Ni and Nj are the classical P1 continuous function  
at vertices i or j.

after all are trivial…

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### Author: ![novelnj](https://avatars.discourse-cdn.com/v4/letter/n/48db29/32.png) [@novelnj](https://community.freefem.org/u/novelnj)
#### Post date: [October 6, 2020, 4:54pm UTC](https://community.freefem.org/t/edge03d-finite-element-assembly/600/3 "2020-10-06T16:54:27Z")

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Thank you, Prof. Hecht. The information is very helpful. Is the sign of the term determined by the order of global node index, like sgn(global\_index(j) - global\_index(i))?

Regards  
Botian Zhang

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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: [October 6, 2020, 7:14pm UTC](https://community.freefem.org/t/edge03d-finite-element-assembly/600/4 "2020-10-06T19:14:41Z")

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yes the edge is oriented i -\> j if i \< j .

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### Author: ![novelnj](https://avatars.discourse-cdn.com/v4/letter/n/48db29/32.png) [@novelnj](https://community.freefem.org/u/novelnj)
#### Post date: [October 6, 2020, 7:53pm UTC](https://community.freefem.org/t/edge03d-finite-element-assembly/600/5 "2020-10-06T19:53:22Z")

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Thank you very much! I have figured it out!.

Regards  
Botian Zhang