2: static char help[] = "Tests binary I/O of matrices and illustrates user-defined event logging.\n\n";

 4:  #include petscmat.h

  6: /* Note:  Most applications would not read and write the same matrix within
  7:   the same program.  This example is intended only to demonstrate
  8:   both input and output. */

 12: int main(int argc,char **args)
 13: {
 14:   Mat            C;
 15:   PetscScalar    v;
 16:   PetscInt       i,j,Ii,J,Istart,Iend,N,m = 4,n = 4;
 17:   PetscMPIInt    rank,size;
 19:   PetscViewer    viewer;
 20:   PetscEvent     MATRIX_GENERATE,MATRIX_READ;

 22:   PetscInitialize(&argc,&args,(char *)0,help);
 23:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
 24:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 25:   PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
 26:   PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
 27:   N = m*n;

 29:   /* PART 1:  Generate matrix, then write it in binary format */


 34:   /* Generate matrix */
 35:   MatCreate(PETSC_COMM_WORLD,&C);
 36:   MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N);
 37:   MatSetFromOptions(C);
 38:   MatGetOwnershipRange(C,&Istart,&Iend);
 39:   for (Ii=Istart; Ii<Iend; Ii++) {
 40:     v = -1.0; i = Ii/n; j = Ii - i*n;
 41:     if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,ADD_VALUES);}
 42:     if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,ADD_VALUES);}
 43:     if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,ADD_VALUES);}
 44:     if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,ADD_VALUES);}
 45:     v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,ADD_VALUES);
 46:   }
 47:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 48:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
 49:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 51:   PetscPrintf(PETSC_COMM_WORLD,"writing matrix in binary to matrix.dat ...\n");
 52:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"matrix.dat",FILE_MODE_WRITE,&viewer);
 53:   MatView(C,viewer);
 54:   PetscViewerDestroy(viewer);
 55:   MatDestroy(C);

 58:   /* PART 2:  Read in matrix in binary format */

 60:   /* All processors wait until test matrix has been dumped */
 61:   MPI_Barrier(PETSC_COMM_WORLD);

 65:   PetscPrintf(PETSC_COMM_WORLD,"reading matrix in binary from matrix.dat ...\n");
 66:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,"matrix.dat",FILE_MODE_READ,&viewer);
 67:   MatLoad(viewer,MATAIJ,&C);
 68:   PetscViewerDestroy(viewer);
 70:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

 72:   /* Free data structures */
 73:   MatDestroy(C);

 75:   PetscFinalize();
 76:   return 0;
 77: }