Actual source code: bipartite.c

      1: #include <petsc/private/matimpl.h>
      2: #include <petscsf.h>

      4: PETSC_EXTERN PetscErrorCode MatColoringCreateBipartiteGraph(MatColoring mc,PetscSF *etoc,PetscSF *etor)
      5: {
      6:   PetscInt          nentries,ncolentries,idx;
      7:   PetscInt          i,j,rs,re,cs,ce,cn;
      8:   PetscInt          *rowleaf,*colleaf,*rowdata;
      9:   PetscInt          ncol;
     10:   const PetscScalar *vcol;
     11:   const PetscInt    *icol;
     12:   const PetscInt    *coldegrees,*rowdegrees;
     13:   Mat               m = mc->mat;

     15:   MatGetOwnershipRange(m,&rs,&re);
     16:   MatGetOwnershipRangeColumn(m,&cs,&ce);
     17:   cn = ce-cs;
     18:   nentries=0;
     19:   for (i=rs;i<re;i++) {
     20:     MatGetRow(m,i,&ncol,NULL,&vcol);
     21:     for (j=0;j<ncol;j++) {
     22:       nentries++;
     23:     }
     24:     MatRestoreRow(m,i,&ncol,NULL,&vcol);
     25:   }
     26:   PetscMalloc1(nentries,&rowleaf);
     27:   PetscMalloc1(nentries,&rowdata);
     28:   idx=0;
     29:   for (i=rs;i<re;i++) {
     30:     MatGetRow(m,i,&ncol,&icol,&vcol);
     31:     for (j=0;j<ncol;j++) {
     32:       rowleaf[idx] = icol[j];
     33:       rowdata[idx] = i;
     34:       idx++;
     35:     }
     36:     MatRestoreRow(m,i,&ncol,&icol,&vcol);
     37:   }
     39:   PetscSFCreate(PetscObjectComm((PetscObject)m),etoc);
     40:   PetscSFCreate(PetscObjectComm((PetscObject)m),etor);

     42:   PetscSFSetGraphLayout(*etoc,m->cmap,nentries,NULL,PETSC_COPY_VALUES,rowleaf);
     43:   PetscSFSetFromOptions(*etoc);

     45:   /* determine the number of entries in the column matrix */
     46:   PetscLogEventBegin(MATCOLORING_Comm,*etoc,0,0,0);
     47:   PetscSFComputeDegreeBegin(*etoc,&coldegrees);
     48:   PetscSFComputeDegreeEnd(*etoc,&coldegrees);
     49:   PetscLogEventEnd(MATCOLORING_Comm,*etoc,0,0,0);
     50:   ncolentries=0;
     51:   for (i=0;i<cn;i++) {
     52:     ncolentries += coldegrees[i];
     53:   }
     54:   PetscMalloc1(ncolentries,&colleaf);

     56:   /* create the one going the other way by building the leaf set */
     57:   PetscLogEventBegin(MATCOLORING_Comm,*etoc,0,0,0);
     58:   PetscSFGatherBegin(*etoc,MPIU_INT,rowdata,colleaf);
     59:   PetscSFGatherEnd(*etoc,MPIU_INT,rowdata,colleaf);
     60:   PetscLogEventEnd(MATCOLORING_Comm,*etoc,0,0,0);

     62:   /* this one takes mat entries in *columns* to rows -- you never have to actually be able to order the leaf entries. */
     63:   PetscSFSetGraphLayout(*etor,m->rmap,ncolentries,NULL,PETSC_COPY_VALUES,colleaf);
     64:   PetscSFSetFromOptions(*etor);

     66:   PetscLogEventBegin(MATCOLORING_Comm,*etor,0,0,0);
     67:   PetscSFComputeDegreeBegin(*etor,&rowdegrees);
     68:   PetscSFComputeDegreeEnd(*etor,&rowdegrees);
     69:   PetscLogEventEnd(MATCOLORING_Comm,*etor,0,0,0);

     71:   PetscFree(rowdata);
     72:   PetscFree(rowleaf);
     73:   PetscFree(colleaf);
     74:   return 0;
     75: }