Actual source code: ex12f.F

  1: !
  2:       program main
  3:        implicit none

 5:  #include finclude/petscsys.h
 6:  #include finclude/petscvec.h
 7:  #include finclude/petscmat.h
 8:  #include finclude/petscpc.h
 9:  #include finclude/petscksp.h
 10:  #include finclude/petscviewer.h
 11: !
 12: !  This example is the Fortran version of ex6.c.  The program reads a PETSc matrix
 13: !  and vector from a file and solves a linear system.  Input arguments are:
 14: !        -f <input_file> : file to load.  For a 5X5 example of the 5-pt. stencil
 15: !                          use the file petsc/src/mat/examples/matbinary.ex
 16: !

 18:       PetscErrorCode  ierr
 19:       PetscInt its,m,n,mlocal,nlocal
 20:       PetscTruth flg
 21:       PetscScalar      norm,none
 22:       Vec              x,b,u
 23:       Mat              A
 24:       character*(128)  f
 25:       PetscViewer      fd
 26:       MatInfo          info(MAT_INFO_SIZE)
 27:       KSP              ksp

 29:       none = -1.0
 30:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)

 32: ! Read in matrix and RHS
 33:       call PetscOptionsGetString(PETSC_NULL_CHARACTER,'-f',f,flg,ierr)
 34:       print *,f
 35:       call PetscViewerBinaryOpen(PETSC_COMM_WORLD,f,FILE_MODE_READ,     &
 36:      &     fd,ierr)

 38:       call MatLoad(fd,MATSEQAIJ,A,ierr)

 40: ! Get information about matrix
 41:       call MatGetSize(A,m,n,ierr)
 42:       call MatGetLocalSize(A,mlocal,nlocal,ierr)
 43:       call MatGetInfo(A,MAT_GLOBAL_SUM,info,ierr)
 44:       write(*,100) m,                                                   &
 45:      &  n,                                                              &
 46:      &  mlocal,nlocal,                                                  &
 47:      &  info(MAT_INFO_BLOCK_SIZE),info(MAT_INFO_NZ_ALLOCATED),          &
 48:      &  info(MAT_INFO_NZ_USED),info(MAT_INFO_NZ_UNNEEDED),              &
 49:      &  info(MAT_INFO_MEMORY),info(MAT_INFO_ASSEMBLIES),                &
 50:      &  info(MAT_INFO_MALLOCS)

 52:  100  format(4(i4,1x),7(g7.1,1x))
 53:       call VecLoad(fd,PETSC_NULL_CHARACTER,b,ierr)
 54:       call PetscViewerDestroy(fd,ierr)

 56: ! Set up solution
 57:       call VecDuplicate(b,x,ierr)
 58:       call VecDuplicate(b,u,ierr)

 60: ! Solve system
 61:       call KSPCreate(PETSC_COMM_WORLD,ksp,ierr)
 62:       call KSPSetOperators(ksp,A,A,DIFFERENT_NONZERO_PATTERN,ierr)
 63:       call KSPSetFromOptions(ksp,ierr)
 64:       call KSPSolve(ksp,b,x,ierr)

 66: ! Show result
 67:       call MatMult(A,x,u,ierr)
 68:       call VecAXPY(u,none,b,ierr)
 69:       call VecNorm(u,NORM_2,norm,ierr)
 70:       call KSPGetIterationNumber(ksp,its,ierr)
 71:       write(6,101) norm,its
 72:  101  format('Residual norm ',e10.4,' iterations ',i5)

 74: ! Cleanup
 75:       call KSPDestroy(ksp,ierr)
 76:       call VecDestroy(b,ierr)
 77:       call VecDestroy(x,ierr)
 78:       call VecDestroy(u,ierr)
 79:       call MatDestroy(A,ierr)

 81:       call PetscFinalize(ierr)
 82:       end