PetscErrorCode PETSCMAT_DLLEXPORT MatConvertFrom_MPIAdj(Mat A,const MatType type,MatReuse reuse,Mat *newmat)
{
Mat B;
PetscErrorCode ierr;
PetscInt i,m,N,nzeros = 0,*ia,*ja,len,rstart,cnt,j,*a;
const PetscInt *rj;
const PetscScalar *ra;
MPI_Comm comm;
PetscFunctionBegin;
ierr = MatGetSize(A,PETSC_NULL,&N);CHKERRQ(ierr);
ierr = MatGetLocalSize(A,&m,PETSC_NULL);CHKERRQ(ierr);
ierr = MatGetOwnershipRange(A,&rstart,PETSC_NULL);CHKERRQ(ierr);
/* count the number of nonzeros per row */
for (i=0; i<m; i++) {
ierr = MatGetRow(A,i+rstart,&len,&rj,PETSC_NULL);CHKERRQ(ierr);
for (j=0; j<len; j++) {
if (rj[j] == i+rstart) {len--; break;} /* don't count diagonal */
}
ierr = MatRestoreRow(A,i+rstart,&len,&rj,PETSC_NULL);CHKERRQ(ierr);
nzeros += len;
}
/* malloc space for nonzeros */
ierr = PetscMalloc((nzeros+1)*sizeof(PetscInt),&a);CHKERRQ(ierr);
ierr = PetscMalloc((N+1)*sizeof(PetscInt),&ia);CHKERRQ(ierr);
ierr = PetscMalloc((nzeros+1)*sizeof(PetscInt),&ja);CHKERRQ(ierr);
nzeros = 0;
ia[0] = 0;
for (i=0; i<m; i++) {
ierr = MatGetRow(A,i+rstart,&len,&rj,&ra);CHKERRQ(ierr);
cnt = 0;
for (j=0; j<len; j++) {
if (rj[j] != i+rstart) { /* if not diagonal */
a[nzeros+cnt] = (PetscInt) PetscAbsScalar(ra[j]);
ja[nzeros+cnt++] = rj[j];
}
}
ierr = MatRestoreRow(A,i+rstart,&len,&rj,&ra);CHKERRQ(ierr);
nzeros += cnt;
ia[i+1] = nzeros;
}
ierr = PetscObjectGetComm((PetscObject)A,&comm);CHKERRQ(ierr);
ierr = MatCreate(comm,&B);CHKERRQ(ierr);
ierr = MatSetSizes(B,m,PETSC_DETERMINE,PETSC_DETERMINE,N);CHKERRQ(ierr);
ierr = MatSetType(B,type);CHKERRQ(ierr);
ierr = MatMPIAdjSetPreallocation(B,ia,ja,a);CHKERRQ(ierr);
if (reuse == MAT_REUSE_MATRIX) {
ierr = MatHeaderReplace(A,B);CHKERRQ(ierr);
} else {
*newmat = B;
}
PetscFunctionReturn(0);
}
/*@C
MatCreateMPIAdj - Creates a sparse matrix representing an adjacency list.
The matrix does not have numerical values associated with it, but is
intended for ordering (to reduce bandwidth etc) and partitioning.
Collective on MPI_Comm
Input Parameters:
+ comm - MPI communicator
. m - number of local rows
. N - number of global columns
. i - the indices into j for the start of each row
. j - the column indices for each row (sorted for each row).
The indices in i and j start with zero (NOT with one).
- values -[optional] edge weights
Output Parameter:
. A - the matrix
Level: intermediate
Notes: This matrix object does not support most matrix operations, include
MatSetValues().
You must NOT free the ii, values and jj arrays yourself. PETSc will free them
when the matrix is destroyed; you must allocate them with PetscMalloc(). If you
call from Fortran you need not create the arrays with PetscMalloc().
Should not include the matrix diagonals.
If you already have a matrix, you can create its adjacency matrix by a call
to MatConvert, specifying a type of MATMPIADJ.
Possible values for MatSetOption() - MAT_STRUCTURALLY_SYMMETRIC
.seealso: MatCreate(), MatConvert(), MatGetOrdering()
@*/
PetscErrorCode PETSCMAT_DLLEXPORT MatCreateMPIAdj(MPI_Comm comm,PetscInt m,PetscInt N,PetscInt *i,PetscInt *j,PetscInt *values,Mat *A)
{
PetscErrorCode ierr;
PetscFunctionBegin;
ierr = MatCreate(comm,A);CHKERRQ(ierr);
ierr = MatSetSizes(*A,m,PETSC_DETERMINE,PETSC_DETERMINE,N);CHKERRQ(ierr);
ierr = MatSetType(*A,MATMPIADJ);CHKERRQ(ierr);
ierr = MatMPIAdjSetPreallocation(*A,i,j,values);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
PETSC_EXTERN void PETSC_STDCALL matmpiadjsetpreallocation_(Mat *mat,PetscInt *i,PetscInt *j,PetscInt *values, PetscErrorCode *ierr)
{
CHKFORTRANNULLINTEGER(values);
*ierr = MatMPIAdjSetPreallocation(*mat,i,j,values);
}
