1c4762a1bSJed Brown 2c4762a1bSJed Brown static char help[] = "Introductory example that illustrates printing.\n\n"; 3c4762a1bSJed Brown 4c4762a1bSJed Brown #include <petscsys.h> 5c4762a1bSJed Brown int main(int argc,char **argv) 6c4762a1bSJed Brown { 7c4762a1bSJed Brown PetscMPIInt rank,size; 8c4762a1bSJed Brown 9c4762a1bSJed Brown /* 10c87e60e8SJose E. Roman Every PETSc program should begin with the PetscInitialize() routine. 11c4762a1bSJed Brown argc, argv - These command line arguments are taken to extract the options 12c4762a1bSJed Brown supplied to PETSc and options supplied to MPI. 13c4762a1bSJed Brown help - When PETSc executable is invoked with the option -help, 14c4762a1bSJed Brown it prints the various options that can be applied at 15c87e60e8SJose E. Roman runtime. The user can use the "help" variable to place 16c4762a1bSJed Brown additional help messages in this printout. 17c4762a1bSJed Brown */ 18*327415f7SBarry Smith PetscFunctionBeginUser; 199566063dSJacob Faibussowitsch PetscCall(PetscInitialize(&argc,&argv,(char*)0,help)); 20c4762a1bSJed Brown 21c4762a1bSJed Brown /* 22c4762a1bSJed Brown The following MPI calls return the number of processes 23c4762a1bSJed Brown being used and the rank of this process in the group. 24c4762a1bSJed Brown */ 259566063dSJacob Faibussowitsch PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD,&size)); 269566063dSJacob Faibussowitsch PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD,&rank)); 27c4762a1bSJed Brown 28c4762a1bSJed Brown /* 29c4762a1bSJed Brown Here we would like to print only one message that represents 30c4762a1bSJed Brown all the processes in the group. We use PetscPrintf() with the 31c4762a1bSJed Brown communicator PETSC_COMM_WORLD. Thus, only one message is 32c4762a1bSJed Brown printed representng PETSC_COMM_WORLD, i.e., all the processors. 33c4762a1bSJed Brown */ 349566063dSJacob Faibussowitsch PetscCall(PetscPrintf(PETSC_COMM_WORLD,"Number of processors = %d, rank = %d\n",size,rank)); 35c4762a1bSJed Brown 36c4762a1bSJed Brown /* 37c4762a1bSJed Brown Here a barrier is used to separate the two program states. 38c4762a1bSJed Brown */ 399566063dSJacob Faibussowitsch PetscCallMPI(MPI_Barrier(PETSC_COMM_WORLD)); 40c4762a1bSJed Brown 41c4762a1bSJed Brown /* 42c4762a1bSJed Brown Here we simply use PetscPrintf() with the communicator PETSC_COMM_SELF, 43c4762a1bSJed Brown where each process is considered separately and prints independently 44c4762a1bSJed Brown to the screen. Thus, the output from different processes does not 45c4762a1bSJed Brown appear in any particular order. 46c4762a1bSJed Brown */ 47c4762a1bSJed Brown 489566063dSJacob Faibussowitsch PetscCall(PetscPrintf(PETSC_COMM_SELF,"[%d] Jumbled Hello World\n",rank)); 49c4762a1bSJed Brown 50c4762a1bSJed Brown /* 51c4762a1bSJed Brown Always call PetscFinalize() before exiting a program. This routine 52c4762a1bSJed Brown - finalizes the PETSc libraries as well as MPI 53c4762a1bSJed Brown - provides summary and diagnostic information if certain runtime 54c4762a1bSJed Brown options are chosen (e.g., -log_view). See PetscFinalize() 55c4762a1bSJed Brown manpage for more information. 56c4762a1bSJed Brown */ 579566063dSJacob Faibussowitsch PetscCall(PetscFinalize()); 58b122ec5aSJacob Faibussowitsch return 0; 59c4762a1bSJed Brown } 60c4762a1bSJed Brown 61c4762a1bSJed Brown /*TEST 62c4762a1bSJed Brown 63c4762a1bSJed Brown test: 64c4762a1bSJed Brown 65c4762a1bSJed Brown TEST*/ 66