2: static char help[] = "Tests converting a parallel AIJ formatted matrix to the parallel Row format.\n\
  3:  This also tests MatGetRow() and MatRestoreRow() for the parallel case.\n\n";

  5: #include <petscmat.h>

  9: int main(int argc,char **args)
 10: {
 11:   Mat               C,A;
 12:   PetscInt          i,j,m = 3,n = 2,Ii,J,rstart,rend,nz;
 13:   PetscMPIInt       rank,size;
 14:   PetscErrorCode    ierr;
 15:   const PetscInt    *idx;
 16:   PetscScalar       v;
 17:   const PetscScalar *values;

 19:   PetscInitialize(&argc,&args,(char*)0,help);
 20:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 21:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 22:   n    = 2*size;

 24:   /* create the matrix for the five point stencil, YET AGAIN*/
 25:   MatCreate(PETSC_COMM_WORLD,&C);
 26:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n);
 27:   MatSetFromOptions(C);
 28:   MatMPIAIJSetPreallocation(C,5,NULL,5,NULL);
 29:   MatSeqAIJSetPreallocation(C,5,NULL);
 30:   for (i=0; i<m; i++) {
 31:     for (j=2*rank; j<2*rank+2; j++) {
 32:       v = -1.0;  Ii = j + n*i;
 33:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 34:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 35:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 36:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
 37:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
 38:     }
 39:   }
 40:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 41:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 42:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);
 43:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);
 44:   PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
 45:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 47:   MatGetOwnershipRange(C,&rstart,&rend);
 48:   for (i=rstart; i<rend; i++) {
 49:     MatGetRow(C,i,&nz,&idx,&values);
 50:     PetscSynchronizedFPrintf(PETSC_COMM_WORLD,stdout,"[%d] get row %D: ",rank,i);
 51:     for (j=0; j<nz; j++) {
 52:       PetscSynchronizedFPrintf(PETSC_COMM_WORLD,stdout,"%D %g  ",idx[j],(double)PetscRealPart(values[j]));
 53:     }
 54:     PetscSynchronizedFPrintf(PETSC_COMM_WORLD,stdout,"\n");
 55:     MatRestoreRow(C,i,&nz,&idx,&values);
 56:   }
 57:   PetscSynchronizedFlush(PETSC_COMM_WORLD,stdout);

 59:   MatConvert(C,MATSAME,MAT_INITIAL_MATRIX,&A);
 60:   PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO);
 61:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);
 62:   PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
 63:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);

 65:   MatDestroy(&A);
 66:   MatDestroy(&C);
 67:   PetscFinalize();
 68:   return 0;
 69: }