Actual source code: ex7.c
petsc-3.9.4 2018-09-11
2: static char help[] = "Demonstrates calling a Fortran computational routine from C.\n\
3: Also demonstrates passing PETSc objects, MPI Communicators from C to Fortran\n\
4: and from Fortran to C\n\n";
6: #include <petscvec.h>
7: /*
8: Ugly stuff to insure the function names match between Fortran
9: and C. Sorry, but this is out of our PETSc hands to cleanup.
10: */
11: /*T
12: Concepts: vectors^fortran-c;
13: Processors: n
14: T*/
15: #include <petsc/private/fortranimpl.h>
16: #if defined(PETSC_HAVE_FORTRAN_CAPS)
17: #define ex7f_ EX7F
18: #define ex7c_ EX7C
19: #elif !defined(PETSC_HAVE_FORTRAN_UNDERSCORE)
20: #define ex7f_ ex7f
21: #define ex7c_ ex7c
22: #endif
24: PETSC_EXTERN void PETSC_STDCALL ex7f_(Vec*,int*);
26: int main(int argc,char **args)
27: {
29: PetscInt m = 10;
30: int fcomm;
31: Vec vec;
33: PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
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 MPI_Comm_c2f() allows
45: translation of the MPI_Comm from C so that it can be properly
46: interpreted from Fortran.
47: */
48: fcomm = MPI_Comm_c2f(PETSC_COMM_WORLD);
50: ex7f_(&vec,&fcomm);
52: VecView(vec,PETSC_VIEWER_STDOUT_WORLD);
53: VecDestroy(&vec);
54: PetscFinalize();
55: return ierr;
56: }
58: PETSC_EXTERN void PETSC_STDCALL ex7c_(Vec *fvec,int *fcomm,PetscErrorCode *ierr)
59: {
60: MPI_Comm comm;
61: PetscInt vsize;
63: /*
64: Translate Fortran integer pointer back to C and
65: Fortran Communicator back to C communicator
66: */
67: comm = MPI_Comm_f2c(*fcomm);
69: /* Some PETSc/MPI operations on Vec/Communicator objects */
70: *VecGetSize(*fvec,&vsize);
71: *MPI_Barrier(comm);
73: }
75: /*TEST
77: build:
78: depends: ex7f.F
79: requires: fortran
81: test:
82: nsize: 3
83: filter: sort -b |grep -v "MPI processes"
84: filter_output: sort -b
86: TEST*/