Actual source code: sprcm.c
petsc-3.7.1 2016-05-15
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      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: */
     10: PETSC_INTERN PetscErrorCode MatGetOrdering_RCM(Mat mat,MatOrderingType type,IS *row,IS *col)
     11: {
     13:   PetscInt       i,*mask,*xls,nrow,*perm;
     14:   const PetscInt *ia,*ja;
     15:   PetscBool      done;

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

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

     25:   /* shift because Sparsepack indices start at one */
     26:   for (i=0; i<nrow; i++) perm[i]--;
     27:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,row);
     28:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,col);
     29:   PetscFree3(mask,perm,xls);
     30:   return(0);
     31: }