1*c4762a1bSJed Brown 2*c4762a1bSJed Brown static char help[] = "Introductory example that illustrates printing.\n\n"; 3*c4762a1bSJed Brown 4*c4762a1bSJed Brown /*T 5*c4762a1bSJed Brown Concepts: introduction to PETSc; 6*c4762a1bSJed Brown Concepts: printing^in parallel 7*c4762a1bSJed Brown Processors: n 8*c4762a1bSJed Brown T*/ 9*c4762a1bSJed Brown 10*c4762a1bSJed Brown 11*c4762a1bSJed Brown 12*c4762a1bSJed Brown #include <petscsys.h> 13*c4762a1bSJed Brown int main(int argc,char **argv) 14*c4762a1bSJed Brown { 15*c4762a1bSJed Brown PetscErrorCode ierr; 16*c4762a1bSJed Brown PetscMPIInt rank,size; 17*c4762a1bSJed Brown 18*c4762a1bSJed Brown /* 19*c4762a1bSJed Brown Every PETSc routine should begin with the PetscInitialize() routine. 20*c4762a1bSJed Brown argc, argv - These command line arguments are taken to extract the options 21*c4762a1bSJed Brown supplied to PETSc and options supplied to MPI. 22*c4762a1bSJed Brown help - When PETSc executable is invoked with the option -help, 23*c4762a1bSJed Brown it prints the various options that can be applied at 24*c4762a1bSJed Brown runtime. The user can use the "help" variable place 25*c4762a1bSJed Brown additional help messages in this printout. 26*c4762a1bSJed Brown */ 27*c4762a1bSJed Brown ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr; 28*c4762a1bSJed Brown 29*c4762a1bSJed Brown /* 30*c4762a1bSJed Brown The following MPI calls return the number of processes 31*c4762a1bSJed Brown being used and the rank of this process in the group. 32*c4762a1bSJed Brown */ 33*c4762a1bSJed Brown ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr); 34*c4762a1bSJed Brown ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr); 35*c4762a1bSJed Brown 36*c4762a1bSJed Brown /* 37*c4762a1bSJed Brown Here we would like to print only one message that represents 38*c4762a1bSJed Brown all the processes in the group. We use PetscPrintf() with the 39*c4762a1bSJed Brown communicator PETSC_COMM_WORLD. Thus, only one message is 40*c4762a1bSJed Brown printed representng PETSC_COMM_WORLD, i.e., all the processors. 41*c4762a1bSJed Brown */ 42*c4762a1bSJed Brown ierr = PetscPrintf(PETSC_COMM_WORLD,"Number of processors = %d, rank = %d\n",size,rank);CHKERRQ(ierr); 43*c4762a1bSJed Brown 44*c4762a1bSJed Brown /* 45*c4762a1bSJed Brown Here a barrier is used to separate the two program states. 46*c4762a1bSJed Brown */ 47*c4762a1bSJed Brown ierr = MPI_Barrier(PETSC_COMM_WORLD);CHKERRQ(ierr); 48*c4762a1bSJed Brown 49*c4762a1bSJed Brown /* 50*c4762a1bSJed Brown Here we simply use PetscPrintf() with the communicator PETSC_COMM_SELF, 51*c4762a1bSJed Brown where each process is considered separately and prints independently 52*c4762a1bSJed Brown to the screen. Thus, the output from different processes does not 53*c4762a1bSJed Brown appear in any particular order. 54*c4762a1bSJed Brown */ 55*c4762a1bSJed Brown 56*c4762a1bSJed Brown ierr = PetscPrintf(PETSC_COMM_SELF,"[%d] Jumbled Hello World\n",rank);CHKERRQ(ierr); 57*c4762a1bSJed Brown 58*c4762a1bSJed Brown /* 59*c4762a1bSJed Brown Always call PetscFinalize() before exiting a program. This routine 60*c4762a1bSJed Brown - finalizes the PETSc libraries as well as MPI 61*c4762a1bSJed Brown - provides summary and diagnostic information if certain runtime 62*c4762a1bSJed Brown options are chosen (e.g., -log_view). See PetscFinalize() 63*c4762a1bSJed Brown manpage for more information. 64*c4762a1bSJed Brown */ 65*c4762a1bSJed Brown ierr = PetscFinalize(); 66*c4762a1bSJed Brown return ierr; 67*c4762a1bSJed Brown } 68*c4762a1bSJed Brown 69*c4762a1bSJed Brown 70*c4762a1bSJed Brown /*TEST 71*c4762a1bSJed Brown 72*c4762a1bSJed Brown test: 73*c4762a1bSJed Brown 74*c4762a1bSJed Brown TEST*/ 75