Actual source code: ex1.c
2: static char help[] = "Introductory example that illustrates printing.\n\n";
4: #include <petscsys.h>
5: int main(int argc,char **argv)
6: {
7: PetscMPIInt rank,size;
9: /*
10: Every PETSc program should begin with the PetscInitialize() routine.
11: argc, argv - These command line arguments are taken to extract the options
12: supplied to PETSc and options supplied to MPI.
13: help - When PETSc executable is invoked with the option -help,
14: it prints the various options that can be applied at
15: runtime. The user can use the "help" variable to place
16: additional help messages in this printout.
17: */
18: PetscInitialize(&argc,&argv,(char*)0,help);
20: /*
21: The following MPI calls return the number of processes
22: being used and the rank of this process in the group.
23: */
24: MPI_Comm_size(PETSC_COMM_WORLD,&size);
25: MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
27: /*
28: Here we would like to print only one message that represents
29: all the processes in the group. We use PetscPrintf() with the
30: communicator PETSC_COMM_WORLD. Thus, only one message is
31: printed representng PETSC_COMM_WORLD, i.e., all the processors.
32: */
33: PetscPrintf(PETSC_COMM_WORLD,"Number of processors = %d, rank = %d\n",size,rank);
35: /*
36: Here a barrier is used to separate the two program states.
37: */
38: MPI_Barrier(PETSC_COMM_WORLD);
40: /*
41: Here we simply use PetscPrintf() with the communicator PETSC_COMM_SELF,
42: where each process is considered separately and prints independently
43: to the screen. Thus, the output from different processes does not
44: appear in any particular order.
45: */
47: PetscPrintf(PETSC_COMM_SELF,"[%d] Jumbled Hello World\n",rank);
49: /*
50: Always call PetscFinalize() before exiting a program. This routine
51: - finalizes the PETSc libraries as well as MPI
52: - provides summary and diagnostic information if certain runtime
53: options are chosen (e.g., -log_view). See PetscFinalize()
54: manpage for more information.
55: */
56: PetscFinalize();
57: return 0;
58: }
60: /*TEST
62: test:
64: TEST*/