1: /*$Id: ex7.c,v 1.33 2001/03/23 23:21:37 balay Exp $*/

  3: static char help[] = "Demonstrates calling a Fortran computational routine from C.n
  4: Also demonstrates passing  PETSc objects, MPI Communicators from C to Fortrann
  5: and from Fortran to Cnn";

 7:  #include petscvec.h

  9: /*
 10:   Ugly stuff to insure the function names match between Fortran 
 11:   and C. Sorry, but this is out of our PETSc hands to cleanup.
 12: */
 13: #if defined(PETSC_HAVE_FORTRAN_CAPS)
 14: #define ex7f_ EX7F
 15: #define ex7c_ EX7C
 16: #elif !defined(PETSC_HAVE_FORTRAN_UNDERSCORE)
 17: #define ex7f_ ex7f
 18: #define ex7c_ ex7c
 19: #endif
 20: EXTERN_C_BEGIN
 21: EXTERN void PETSC_STDCALL ex7f_(Vec *,int*);
 22: EXTERN_C_END

 24: #undef __FUNCT__
 26: int main(int argc,char **args)
 27: {
 28:   int              ierr,m = 10;
 29:   int              fcomm;
 30:   Vec              vec;

 32:   PetscInitialize(&argc,&args,(char *)0,help);

 34:   /* This function should be called to be able to use PETSc routines
 35:      from the FORTRAN subroutines needed by this program */

 37:   PetscInitializeFortran();

 39:   VecCreate(PETSC_COMM_WORLD,&vec);
 40:   VecSetSizes(vec,PETSC_DECIDE,m);
 41:   VecSetFromOptions(vec);

 43:   /* 
 44:      Call Fortran routine - the use of MPICCommToFortranComm() allows 
 45:      translation of the MPI_Comm from C so that it can be properly 
 46:      interpreted from Fortran.
 47:   */
 48:   MPICCommToFortranComm(PETSC_COMM_WORLD,&fcomm);

 50:   ex7f_(&vec,&fcomm);

 52:   VecView(vec,PETSC_VIEWER_STDOUT_WORLD);
 53:   VecDestroy(vec);
 54:   PetscFinalize();
 55:   return 0;
 56: }

 58: EXTERN_C_BEGIN
 59: #undef __FUNCT__
 61: void PETSC_STDCALL ex7c_(Vec *fvec,int *fcomm,int* ierr)
 62: {
 63:   MPI_Comm comm;
 64:   int size;

 66:   /*
 67:     Translate Fortran integer pointer back to C and
 68:     Fortran Communicator back to C communicator
 69:   */
 70:   *MPIFortranCommToCComm(*fcomm,&comm);
 71: 
 72:   /* Some PETSc/MPI operations on Vec/Communicator objects */
 73:   *VecGetSize(*fvec,&size);
 74:   *MPI_Barrier(comm);

 76: }
 77: EXTERN_C_END