3.2 Mesh Entity Manipulation

int FEM_Mesh_default_read(void);
INTEGER function :: FEM_Mesh_default_read()

Return the default reading mesh. This routine is valid:

• From driver(), to return the partitioned mesh.
• During your FEM_Update_mesh routine, to return the assembled mesh.
• Anytime after a call to FEM_Mesh_set_default_read.

int FEM_Mesh_default_write(void);
INTEGER function :: FEM_Mesh_default_write()

Return the default writing mesh. This routine is valid:

• From init(), to change the new serial mesh.
• From driver(), to change the new partitioned mesh.
• During your FEM_Update_mesh routine, to change the new serial mesh.
• Anytime after a call to FEM_Mesh_set_default_write.

int FEM_Mesh_get_length(int mesh,int entity);
INTEGER function :: FEM_Mesh_get_length(mesh,entity)
INTEGER, INTENT(IN) :: mesh,entity

Return the number of entitys that exist in this mesh.

This call can be used with any entity. For example, to get the number of nodes,

      nNodes=FEM_Mesh_get_length(mesh,FEM_NODE)
  

To get the number of ghost nodes,

      nGhostNodes=FEM_Mesh_get_length(mesh,FEM_GHOST+FEM_NODE)
  

To get the number of real elements of type 2,

   nElem=FEM_Mesh_get_length(mesh,FEM_ELEM+2)
  

void FEM_Mesh_data(int mesh,int entity,int attr, void *data, int first, int length, int datatype,int width);
SUBROUTINE FEM_Mesh_data(mesh,entity,attr,data,first,length,datatype,width)
INTEGER, INTENT(IN) :: mesh,entity,attr,first,length,datatype,width
datatype, intent(inout) :: data(width,length)

This is the one routine for getting or setting entity's attributes on the mesh.

• mesh A FEM mesh object. Depending on whether this is a reading or writing mesh, this routine reads from or writes to the data array you pass in.

• entity A FEM entity code, for example FEM_NODE or FEM_GHOST+FEM_ELEM+1.

• attr A FEM attribute code, for example FEM_DATA+ or FEM_CONN.

• data The user data to get or set. Each row of this array consists of width values, and contains the data values of the attribute for the corresponding entity. This data must be formatted as one of:
        datatype :: data(width,length)
        datatype :: data(width*length)
    

• first The first entity to affect. In C, this is normally 0; in Fortran, this is normally 1.

• length The number of entities to affect. The entities affected are thus those numbered from first to first+length-1. For now, length must be either 1, to touch a single entity; or else the total number of entities-that is, FEM_Mesh_get_length(mesh,entity).

• datatype The data type stored in this attribute. This is one of the standard FEM data types FEM_BYTE, FEM_INT, FEM_FLOAT, or FEM_DOUBLE; or else the C-style 0-based index type FEM_INDEX_0 or the Fortran-style 1-based index type FEM_INDEX_1. Alternatively, the equivalent types IDXL_BYTE, IDXL_INT, IDXL_FLOAT, IDXL_DOUBLE, IDXL_INDEX_0, or IDXL_INDEX_1 may be used.

• width The number of data items per entity.

For example, to set the element connectivity, which is stored as 3 integer node indices in nodes, you would:

/* C version */
   int *nodes=new int[3*nElems];
   ... fill out nodes ...
   FEM_Mesh_data(mesh,FEM_ELEM+1,FEM_CONN, nodes, 0,nElems, FEM_INDEX_0, 3);
   ... continue to use or delete nodes ...
   
! F90 version
   ALLOCATE(nodes(3,nElems))
   ... fill out nodes ...
   CALL FEM_Mesh_data(mesh,FEM_ELEM+1,FEM_CONN, nodes, 1,nElems, FEM_INDEX_1, 3)
   ... continue to use or delete nodes ...
  

To add a new node property with 2 double-precision numbers from an array mat (containing, for example, material properties), you would first pick an unused user data "tag", for example 13, and:

/* C version */
   double *mat=new double[2*nNodes];
   ...
   FEM_Mesh_data(mesh,FEM_NODE, FEM_DATA+13, mat, 0,nNodes, FEM_DOUBLE, 2);
   
! F90 version
   ALLOCATE(mat(2,nNodes))
   CALL FEM_Mesh_data(mesh,FEM_NODE,FEM_DATA+13, mat, 1,nNodes, FEM_DOUBLE, 2)