2: static char help[] = "Tests MatIncreaseOverlap() and MatGetSubmatrices() for the parallel case.\n\
  3: This example is similar to ex40.c; here the index sets used are random.\n\
  4: Input arguments are:\n\
  5:   -f <input_file> : file to load.  For a 5X5 example of the 5-pt. stencil,\n\
  6:                        use the file petsc/src/mat/examples/matbinary.ex\n\
  7:   -nd <size>      : > 0  no of domains per processor \n\
  8:   -ov <overlap>   : >=0  amount of overlap between domains\n\n";

 10:  #include petscksp.h

 14: int main(int argc,char **args)
 15: {
 17:   PetscInt       nd = 2,ov=1,i,j,lsize,m,n,*idx;
 18:   PetscMPIInt    rank;
 19:   PetscTruth     flg;
 20:   Mat            A,B,*submatA,*submatB;
 21:   char           file[PETSC_MAX_PATH_LEN];
 22:   PetscViewer    fd;
 23:   IS             *is1,*is2;
 24:   PetscRandom    r;
 25:   PetscScalar    rand;

 27:   PetscInitialize(&argc,&args,(char *)0,help);
 28: #if defined(PETSC_USE_COMPLEX)
 29:   SETERRQ(1,"This example does not work with complex numbers");
 30: #else
 31: 
 32:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 33:   PetscOptionsGetString(PETSC_NULL,"-f",file,PETSC_MAX_PATH_LEN-1,PETSC_NULL);
 34:   PetscOptionsGetInt(PETSC_NULL,"-nd",&nd,PETSC_NULL);
 35:   PetscOptionsGetInt(PETSC_NULL,"-ov",&ov,PETSC_NULL);

 37:   /* Read matrix and RHS */
 38:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);
 39:   MatLoad(fd,MATMPIAIJ,&A);
 40:   PetscViewerDestroy(fd);

 42:   /* Read the matrix again as a seq matrix */
 43:   PetscViewerBinaryOpen(PETSC_COMM_SELF,file,FILE_MODE_READ,&fd);
 44:   MatLoad(fd,MATSEQAIJ,&B);
 45:   PetscViewerDestroy(fd);
 46: 
 47:   /* Create the Random no generator */
 48:   MatGetSize(A,&m,&n);
 49:   PetscRandomCreate(PETSC_COMM_SELF,&r);
 50:   PetscRandomSetFromOptions(r);

 52:   /* Create the IS corresponding to subdomains */
 53:   PetscMalloc(nd*sizeof(IS **),&is1);
 54:   PetscMalloc(nd*sizeof(IS **),&is2);
 55:   PetscMalloc(m *sizeof(PetscInt),&idx);
 56: 
 57:   /* Create the random Index Sets */
 58:   for (i=0; i<nd; i++) {
 59:     /* Skip a few,so that the IS on different procs are diffeent*/
 60:     for (j=0; j<rank; j++) {
 61:       PetscRandomGetValue(r,&rand);
 62:     }
 63:     PetscRandomGetValue(r,&rand);
 64:     lsize   = (PetscInt)(rand*m);
 65:     for (j=0; j<lsize; j++) {
 66:       PetscRandomGetValue(r,&rand);
 67:       idx[j] = (PetscInt)(rand*m);
 68:     }
 69:     PetscSortInt(lsize,idx);
 70:     ISCreateGeneral(PETSC_COMM_SELF,lsize,idx,is1+i);
 71:     ISCreateGeneral(PETSC_COMM_SELF,lsize,idx,is2+i);
 72:   }

 74:   MatIncreaseOverlap(A,nd,is1,ov);
 75:   MatIncreaseOverlap(B,nd,is2,ov);

 77:   for (i=0; i<nd; ++i) {
 78:     ISSort(is1[i]);
 79:     ISSort(is2[i]);
 80:   }
 81: 
 82:   MatGetSubMatrices(A,nd,is1,is1,MAT_INITIAL_MATRIX,&submatA);
 83:   MatGetSubMatrices(B,nd,is2,is2,MAT_INITIAL_MATRIX,&submatB);
 84: 
 85:   /* Now see if the serial and parallel case have the same answers */
 86:   for (i=0; i<nd; ++i) {
 87:     MatEqual(submatA[i],submatB[i],&flg);
 88:     PetscPrintf(PETSC_COMM_SELF,"proc:[%d], i=%D, flg =%d\n",rank,i,(int)flg);
 89:   }

 91:   /* Free Allocated Memory */
 92:   for (i=0; i<nd; ++i) {
 93:     ISDestroy(is1[i]);
 94:     ISDestroy(is2[i]);
 95:     MatDestroy(submatA[i]);
 96:     MatDestroy(submatB[i]);
 97:   }
 98:   PetscFree(submatA);
 99:   PetscFree(submatB);
100:   PetscRandomDestroy(r);
101:   PetscFree(is1);
102:   PetscFree(is2);
103:   MatDestroy(A);
104:   MatDestroy(B);
105:   PetscFree(idx);

107:   PetscFinalize();
108: #endif
109:   return 0;
110: }