**Synopsis**

```
PIDs = gf_mesh_set(mesh M, 'pts', mat PTS)
PIDs = gf_mesh_set(mesh M, 'add point', mat PTS)
gf_mesh_set(mesh M, 'del point', ivec PIDs)
CVIDs = gf_mesh_set(mesh M, 'add convex', geotrans GT, mat PTS)
gf_mesh_set(mesh M, 'del convex', mat CVIDs)
gf_mesh_set(mesh M, 'del convex of dim', ivec DIMs)
gf_mesh_set(mesh M, 'translate', vec V)
gf_mesh_set(mesh M, 'transform', mat T)
gf_mesh_set(mesh M, 'boundary', int rnum, mat CVFIDs)
gf_mesh_set(mesh M, 'region', int rnum, mat CVFIDs)
gf_mesh_set(mesh M, 'extend region', int rnum, mat CVFIDs)
gf_mesh_set(mesh M, 'region intersect', int r1, int r2)
gf_mesh_set(mesh M, 'region merge', int r1, int r2)
gf_mesh_set(mesh M, 'region subtract', int r1, int r2)
gf_mesh_set(mesh M, 'delete boundary', int rnum, mat CVFIDs)
gf_mesh_set(mesh M, 'delete region', ivec RIDs)
gf_mesh_set(mesh M, 'merge', mesh m2[, scalar tol])
gf_mesh_set(mesh M, 'optimize structure'[, int with_renumbering])
gf_mesh_set(mesh M, 'refine'[, ivec CVIDs])
```

**Description :**

General function for modification of a mesh object.

**Command list :**

PIDs = gf_mesh_set(mesh M, 'pts', mat PTS)Replace the coordinates of the mesh points with those given in PTS.

PIDs = gf_mesh_set(mesh M, 'add point', mat PTS)Insert new points in the mesh and return their #ids.

PTS should be an

nxmmatrix , wherenis the mesh dimension, andmis the number of points that will be added to the mesh. On output, PIDs contains the point #ids of these new points.Remark: if some points are already part of the mesh (with a small tolerance of approximately

1e-8), they won’t be inserted again, and PIDs will contain the previously assigned #ids of these points.

gf_mesh_set(mesh M, 'del point', ivec PIDs)Removes one or more points from the mesh.

PIDs should contain the point #ids, such as the one returned by the ‘add point’ command.

CVIDs = gf_mesh_set(mesh M, 'add convex', geotrans GT, mat PTS)Add a new convex into the mesh.

The convex structure (triangle, prism,...) is given by GT (obtained with gf_geotrans(‘...’)), and its points are given by the columns of PTS. On return, CVIDs contains the convex #ids. PTS might be a 3-dimensional array in order to insert more than one convex (or a two dimensional array correctly shaped according to Fortran ordering).

gf_mesh_set(mesh M, 'del convex', mat CVIDs)Remove one or more convexes from the mesh.

CVIDs should contain the convexes #ids, such as the ones returned by the ‘add convex’ command.

gf_mesh_set(mesh M, 'del convex of dim', ivec DIMs)Remove all convexes of dimension listed in DIMs.

For example;

gf_mesh_set(mesh M, 'del convex of dim', [1,2])remove all line segments, triangles and quadrangles.

gf_mesh_set(mesh M, 'translate', vec V)Translates each point of the mesh from V.

gf_mesh_set(mesh M, 'transform', mat T)Applies the matrix T to each point of the mesh.

Note that T is not required to be a

NxNmatrix (withN = gf_mesh_get(mesh M, 'dim')). Hence it is possible to transform a 2D mesh into a 3D one (and reciprocally).

gf_mesh_set(mesh M, 'boundary', int rnum, mat CVFIDs)DEPRECATED FUNCTION. Use ‘region’ instead.

gf_mesh_set(mesh M, 'region', int rnum, mat CVFIDs)Assigns the region number rnum to the set of convexes or/and convex faces provided in the matrix CVFIDs.

The first row of CVFIDs contains convex #ids, and the second row contains a face number in the convex (or 0 for the whole convex (regions are usually used to store a list of convex faces, but you may also use them to store a list of convexes).

If a vector is provided (or a one row matrix) the region will represent the corresponding set of convex.

gf_mesh_set(mesh M, 'extend region', int rnum, mat CVFIDs)Extends the region identified by the region number rnum to include the set of convexes or/and convex faces provided in the matrix CVFIDs, see alsogf_mesh_set(mesh M, 'set region).

gf_mesh_set(mesh M, 'region intersect', int r1, int r2)Replace the region number r1 with its intersection with region number r2.

gf_mesh_set(mesh M, 'region merge', int r1, int r2)Merge region number r2 into region number r1.

gf_mesh_set(mesh M, 'region subtract', int r1, int r2)Replace the region number r1 with its difference with region number r2.

gf_mesh_set(mesh M, 'delete boundary', int rnum, mat CVFIDs)DEPRECATED FUNCTION. Use ‘delete region’ instead.

gf_mesh_set(mesh M, 'delete region', ivec RIDs)Remove the regions whose #ids are listed in RIDs

gf_mesh_set(mesh M, 'merge', mesh m2[, scalar tol])Merge with the mesh m2.

Overlapping points, within a tolerance radius tol, will not be duplicated. If m2 is a mesh_fem object, its linked mesh will be used.

gf_mesh_set(mesh M, 'optimize structure'[, int with_renumbering])Reset point and convex numbering.

After optimisation, the points (resp. convexes) will be consecutively numbered from 1 to gf_mesh_get(mesh M, ‘max pid’) (resp. gf_mesh_get(mesh M, ‘max cvid’)).

gf_mesh_set(mesh M, 'refine'[, ivec CVIDs])Use a Bank strategy for mesh refinement.

If CVIDs is not given, the whole mesh is refined. Note that the regions, and the finite element methods and integration methods of the mesh_fem and mesh_im objects linked to this mesh will be automagically refined.