# [petsc-users] Plex mesh reference element

Matthew Knepley knepley at gmail.com
Mon Feb 17 07:28:32 CST 2014

```On Tue, Feb 11, 2014 at 7:50 AM, Dharmendar Reddy
<dharmareddy84 at gmail.com>wrote:

> Hello,
>        Where do i find the information on reference elements used by
> plex for local numbering.
>

You can use

PetscDualSpaceCreateReferenceCell(sp, dim, isSimplex, &refCell)
PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,
PETSC_VIEWER_ASCII_INFO_DETAIL)
DMView(refCell, PETSC_VIEWER_STDOUT_WORLD)

Matt

I currently use the following for the tetrahedron. Is this correct ?
> what is the corresponding information for a  triangle ?
>
>         ! Vertex coordiantes
>        vert(1:3,1)=[0.0, 0.0, 0.0]
>         vert(1:3,2)=[1.0, 0.0, 0.0]
>         vert(1:3,3)=[0.0, 1.0, 0.0]
>         vert(1:3,4)=[0.0, 0.0, 1.0]
>
>         ! vertex intdices
>         vs(1:4)= [1, 2, 3, 4]
>
>         ! Edges id to node Id
>         edge(:,1) = [3, 4]
>         edge(:,2) = [2, 4]
>         edge(:,3) = [2, 3]
>         edge(:,4) = [1, 4]
>         edge(:,5) = [1, 3]
>         edge(:,6) = [1, 2]
>
>         ! Faces id to node id
>         face(1:3,1)=[2,3,4]
>         face(1:3,2)=[1,3,4]
>         face(1:3,3)=[1,2,4]
>         face(1:3,4)=[1,2,3]
>         numFacet = 4
>
>         ! Tets
>         tet(1:4,1) = [1,2,3,4]
> thanks
> Reddy
>

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