Date: 2022-03-04T17:38:19+00:00

Actual source code: sprcm.c

      2: #include <petscmat.h>
      3: #include <petsc/private/matorderimpl.h>

      5: /*
      6:     MatGetOrdering_RCM - Find the Reverse Cuthill-McKee ordering of a given matrix.
      7: */
      8: PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat,MatOrderingType type,IS *row,IS *col)
      9: {
     11:   PetscInt       i,*mask,*xls,nrow,*perm;
     12:   const PetscInt *ia,*ja;
     13:   PetscBool      done;

     16:   MatGetRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,&nrow,&ia,&ja,&done);
     17:   if (!done) SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot get rows for matrix");

     19:   PetscMalloc3(nrow,&mask,nrow,&perm,2*nrow,&xls);
     20:   SPARSEPACKgenrcm(&nrow,ia,ja,perm,mask,xls);
     21:   MatRestoreRowIJ(mat,1,PETSC_TRUE,PETSC_TRUE,NULL,&ia,&ja,&done);

     23:   /* shift because Sparsepack indices start at one */
     24:   for (i=0; i<nrow; i++) perm[i]--;
     25:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,row);
     26:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,col);
     27:   PetscFree3(mask,perm,xls);
     28:   return(0);
     29: }