2: static char help[] = "Tests MatGetArray().\n\n";

 4:  #include petscmat.h

  8: int main(int argc,char **args)
  9: {
 10:   Mat              A;
 11:   PetscInt         i,j,m = 3,n = 2,rstart,rend;
 12:   PetscErrorCode   ierr;
 13:   PetscScalar      v,*array;

 15:   PetscInitialize(&argc,&args,(char *)0,help);

 17:   /*
 18:       Create a parallel dense matrix shared by all processors 
 19:   */
 20:   MatCreateMPIDense(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,m,n,PETSC_NULL,&A);
 21: 

 23:   /*
 24:      Set values into the matrix 
 25:   */
 26:   for (i=0; i<m; i++) {
 27:     for (j=0; j<n; j++) {
 28:       v = 9.0/(i+j+1); MatSetValues(A,1,&i,1,&j,&v,INSERT_VALUES);
 29:     }
 30:   }
 31:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 32:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 34:   /*
 35:        Print the matrix to the screen 
 36:   */
 37:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);


 40:   /*
 41:       Print the local portion of the matrix to the screen
 42:   */
 43:   MatGetArray(A,&array);
 44:   MatGetOwnershipRange(A,&rstart,&rend);
 45:   for (i=rstart; i<rend; i++) {
 46:     for (j=0; j<n; j++) {
 47:       PetscSynchronizedPrintf(PETSC_COMM_WORLD,"%6.4e ",PetscRealPart(array[j*(rend-rstart)+i-rstart]));
 48:     }
 49:     PetscSynchronizedPrintf(PETSC_COMM_WORLD,"\n");
 50:   }
 51:   PetscSynchronizedFlush(PETSC_COMM_WORLD);
 52:   MatRestoreArray(A,&array);

 54:   /*
 55:       Free the space used by the matrix
 56:   */
 57:   MatDestroy(A);
 58:   PetscFinalize();
 59:   return 0;
 60: }