2: static char help[] = "Demonstrates using the PetscBag Object\n\n";

  4: /*T
  5:    Concepts: bags;
  6:    Processors: n
  7: T*/
  8: #include <petscsys.h>
  9: #include <petscbag.h>

 11: /*
 12:   Enum variables can be stored in a bag but require a string array
 13:   to name their fields.  The fourth entry in this example is the name 
 14:   of the enum, the fifth is the prefix (none in this case), and the last 
 15:   entry is the null string.
 16: */
 17: typedef enum {
 18:   THIS = 0, THAT = 1, THE_OTHER = 2
 19: } YourChoice;
 20: const char *EnumeratedChoices[] = {"THIS","THAT","THE_OTHER","EnumeratedChoices","",0};

 22: /*
 23:   Data structures can be used in a bag as long as they 
 24:   are declared in the bag with a variable, not with a pointer.
 25: */
 26: typedef struct {
 27:   PetscReal   x1,x2;
 28: } TwoVec;

 30: /* 
 31:   Define a C struct that will contain my program's parameters.
 32: */
 33: typedef struct {
 34:   PetscScalar   W;
 35:   PetscReal     rho;
 36:   TwoVec        pos;
 37:   PetscInt      Ii;
 38:   PetscBool     T;
 39:   PetscDataType dt;
 40:   char          filename[PETSC_MAX_PATH_LEN];
 41:   YourChoice    which;
 42: } Parameter;
 43: 

 47: int main(int argc,char **argv)
 48: {
 50:   PetscBag       bag;
 51:   Parameter      *params;
 52:   PetscViewer    viewer;
 53:   PetscBool      flg;
 54:   char           filename[PETSC_MAX_PATH_LEN] = "binaryoutput";

 56:   /*
 57:     Every PETSc routine should begin with the PetscInitialize() routine.
 58:     argc, argv - These command line arguments are taken to extract the options
 59:                  supplied to PETSc and options supplied to MPI.
 60:     help       - When PETSc executable is invoked with the option -help, 
 61:                  it prints the various options that can be applied at 
 62:                  runtime.  The user can use the "help" variable place
 63:                  additional help messages in this printout.
 64:   */
 65:   PetscInitialize(&argc,&argv,(char *)0,help);

 67:   /* Create an empty bag */
 68:   PetscBagCreate(PETSC_COMM_WORLD,sizeof(Parameter),&bag);
 69:   PetscBagGetData(bag,(void **)&params);
 70: 
 71:   /* register variables, defaults, names, help strings */
 72:   PetscBagSetName(bag,"ParameterBag","contains parameters for simulations of top-secret, dangerous physics");
 73:   PetscBagSetOptionsPrefix(bag, "pbag_");
 74:   PetscBagRegisterString(bag,&params->filename,PETSC_MAX_PATH_LEN,"myfile","filename","Name of secret file");
 75:   PetscBagRegisterReal  (bag,&params->rho,3.0,"rho","Density, kg/m^3");
 76:   PetscBagRegisterScalar(bag,&params->W,  5.0,"W","Vertical velocity, m/sec");
 77:   PetscBagRegisterInt   (bag,&params->Ii, 2,"modes_x","Number of modes in x-direction");
 78:   PetscBagRegisterBool (bag,&params->T,  PETSC_FALSE,"do_output","Write output file (yes/no)");
 79:   PetscBagRegisterEnum  (bag,&params->dt, PetscDataTypes,(PetscEnum)PETSC_INT,"dt","meaningless datatype");
 80:   PetscBagRegisterReal  (bag,&params->pos.x1,1.0,"x1","x position");
 81:   PetscBagRegisterReal  (bag,&params->pos.x2,1.9,"x2","y position");
 82:   PetscBagRegisterEnum  (bag,&params->which, EnumeratedChoices, (PetscEnum)THAT, "choose","Express yourself by choosing among enumerated things");

 84: 
 85:   /* This option allows loading user-provided PetscBag */
 86:   PetscOptionsGetString(PETSC_NULL,"-f",filename,sizeof filename,&flg);
 87:   if (!flg) {

 89:     /* write bag to stdio & binary file */
 90:     PetscBagView(bag,PETSC_VIEWER_STDOUT_WORLD);
 91:     PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_WRITE,&viewer);
 92:     PetscBagView(bag,viewer);
 93:     PetscViewerDestroy(&viewer);
 94:   }
 95: 
 96:   PetscMemzero(params,sizeof(params));

 98:   /* load bag from file & write to stdio */
 99:   PetscViewerBinaryOpen(PETSC_COMM_WORLD,filename,FILE_MODE_READ,&viewer);
100:   PetscBagLoad(viewer,bag);
101:   PetscViewerDestroy(&viewer);
102:   PetscBagSetFromOptions(bag);
103:   PetscBagView(bag,PETSC_VIEWER_STDOUT_WORLD);

105:   /* reuse the parameter struct */
106:   PetscBagGetData(bag,(void**)&params);
107:   PetscPrintf(PETSC_COMM_WORLD,"The value of rho after loading is: %f\n",(double)params->rho);

109: #if defined(PETSC_USE_SOCKET_VIEWER)
110:   {
111:     PetscBool  flg;
112:     PetscOptionsName("-bag_view_socket","Sends bag to socket (can be read from matlab)","PetscBagView",&flg);
113:     if (flg) {
114:       PetscBagView(bag,PETSC_VIEWER_SOCKET_(PETSC_COMM_WORLD));
115:       PetscViewerFlush(PETSC_VIEWER_SOCKET_(PETSC_COMM_WORLD));
116:     }
117:   }
118: #endif

120:   /* clean up and exit */
121:   PetscBagDestroy(&bag);
122:   PetscFinalize();
123:   return 0;
124: }