Actual source code: natural.c

petsc-3.7.5 2017-01-01
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  1: #include <petsc/private/matimpl.h>      /*I "petscmat.h"  I*/
  2: #include <petsc/private/isimpl.h>

  6: static PetscErrorCode MatColoringApply_Natural(MatColoring mc,ISColoring *iscoloring)
  7: {
  8:   PetscErrorCode  ierr;
  9:   PetscInt        start,end,i,bs = 1,n;
 10:   ISColoringValue *colors;
 11:   MPI_Comm        comm;
 12:   PetscBool       flg1,flg2;
 13:   Mat             mat     = mc->mat;
 14:   Mat             mat_seq = mc->mat;
 15:   PetscMPIInt     size;
 16:   ISColoring      iscoloring_seq;
 17:   ISColoringValue *colors_loc;
 18:   PetscInt        rstart,rend,N_loc,nc;

 21:   /* this is ugly way to get blocksize but cannot call MatGetBlockSize() because AIJ can have bs > 1 */
 22:   PetscObjectTypeCompare((PetscObject)mat,MATSEQBAIJ,&flg1);
 23:   PetscObjectTypeCompare((PetscObject)mat,MATMPIBAIJ,&flg2);
 24:   if (flg1 || flg2) {
 25:     MatGetBlockSize(mat,&bs);
 26:   }

 28:   PetscObjectGetComm((PetscObject)mat,&comm);
 29:   MPI_Comm_size(comm,&size);
 30:   if (size > 1) {
 31:     /* create a sequential iscoloring on all processors */
 32:     MatGetSeqNonzeroStructure(mat,&mat_seq);
 33:   }

 35:   MatGetSize(mat_seq,&n,NULL);
 36:   MatGetOwnershipRange(mat_seq,&start,&end);
 37:   n    = n/bs;
 38:   if (n > IS_COLORING_MAX-1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Maximum color size exceeded");

 40:   start = start/bs;
 41:   end   = end/bs;
 42:   PetscMalloc1(end-start+1,&colors);
 43:   for (i=start; i<end; i++) {
 44:     colors[i-start] = (ISColoringValue)i;
 45:   }
 46:   ISColoringCreate(comm,n,end-start,colors,PETSC_OWN_POINTER,iscoloring);

 48:   if (size > 1) {
 49:     MatDestroySeqNonzeroStructure(&mat_seq);

 51:     /* convert iscoloring_seq to a parallel iscoloring */
 52:     iscoloring_seq = *iscoloring;
 53:     rstart         = mat->rmap->rstart/bs;
 54:     rend           = mat->rmap->rend/bs;
 55:     N_loc          = rend - rstart; /* number of local nodes */

 57:     /* get local colors for each local node */
 58:     PetscMalloc1(N_loc+1,&colors_loc);
 59:     for (i=rstart; i<rend; i++) {
 60:       colors_loc[i-rstart] = iscoloring_seq->colors[i];
 61:     }
 62:     /* create a parallel iscoloring */
 63:     nc   = iscoloring_seq->n;
 64:     ISColoringCreate(comm,nc,N_loc,colors_loc,PETSC_OWN_POINTER,iscoloring);
 65:     ISColoringDestroy(&iscoloring_seq);
 66:   }
 67:   return(0);
 68: }

 72: PETSC_EXTERN PetscErrorCode MatColoringCreate_Natural(MatColoring mc)
 73: {
 75:     mc->data                = NULL;
 76:     mc->ops->apply          = MatColoringApply_Natural;
 77:     mc->ops->view           = NULL;
 78:     mc->ops->destroy        = NULL;
 79:     mc->ops->setfromoptions = NULL;
 80:     return(0);
 81: }