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NAME

       mpif77 - Compile LAM FORTRAN programs.

SYNOPSIS

       mpif77 [-showme|-showme:compile|-showme:link] ...

OPTIONS

       -showme
              Does  not  invoke  the  underlying  FORTRAN  compiler.   Instead, it shows the full
              command line that would be executed to compile the FORTRAN program.

       -showme:compile
              Does not invoke the underlying FORTRAN compiler.  Instead, it  shows  the  compiler
              flags that would be supplied to the FORTRAN compiler.

       -showme:link
              Does  not  invoke  the  underlying  FORTRAN compiler.  Instead, it shows the linker
              flags that would be supplied to the FORTRAN compiler.

       See f77(1) (or whatever your underlying FORTRAN compiler is) for all other options.

DESCRIPTION

       mpif77 is a convenience wrapper for the local native FORTRAN compiler.  Translation  of  a
       LAM  program  requires  the  linkage of the LAM essential services libraries which may not
       reside in one of the standard search directories of ld(1).  mpif77  passes  its  arguments
       along  to  the  local native FORTRAN compiler along with the -L and -l options required by
       LAM/MPI programs.  This includes all necessary  options  for  ROMIO  and/or  C++  bindings
       support (if ROMIO/C++ support was included when LAM was compiled).

       The  LAM  Team  strongly  encourages using mpif77 instead of attempting to link to the LAM
       libraries manually.  This allows the specific implementation  of  LAM  to  change  without
       forcing  changes  to linker directives in users' Makefiles (the specific set of underlying
       LAM libraries has already changed multiple times, and will likely change again  in  future
       versions).

       Indeed,  since  mpif77  is a very thin wrapper on top of an underlying compiler, there are
       very, very few compelling reasons not to use mpif77.  When  it  is  not  possible  to  use
       mpif77,  the  -showme:compile  and  -showme:link  arguments  should  be used instead.  For
       example:

       shell$ f77 -c file1.f `mpif77 -showme:compile`

       shell$ f77 -c file2.f `mpif77 -showme:compile`

       shell$ f77 file1.o file2.o `mpif77 -showme:link` -o my_mpi_program

ENVIRONMENT VARIABLES

       By default, mpif77 uses the FORTRAN compiler that was selected  when  LAM  was  configured
       (with  the  --with-fc  flag to ./configure) as the local native FORTRAN compiler, but this
       can be  overridden  by  the  LAMMPIF77  environment  variable  (an  older  name  for  this
       environment variable is LAMHF77 -- this also still works, but its use is deprecated).

       If  the  environment variable LAMHOME is set, mpif77 will use its value as the location of
       the LAM installation directory instead of the value that was compiled into  mpif77.   This
       means  that  mpif77  will  use  the  value  of LAMHOME as the base to create the -I and -L
       arguments that are passed to the lower-level compiler, not the installation directory that
       was supplied when mpif77 was created.  This is almost always a Bad Idea.

       The  use  of  LAMHOME  is  discouraged  except  for some rare configuration cases in oddly
       networked sites (in which case your system administrator should probably set this up), and
       for  advanced  users  with  multiple  LAM/MPI  installations who really know what they are
       doing; if the LAMHOME environment variable is unintentionally left set,  it  can  lead  to
       tremendous  user confusion.  For example, if LAMHOME points to LAM installation A, but the
       user's PATH points to LAM installation B, then even though B's mpif77 will  be  used,  the
       user program will be compiled and linked against LAM installation A.

       The LAMHOME environment variable is mainly only left in place for backwards compatibility;
       it is not required for normal functioning of LAM/MPI.  The LAM Team discourages the use of
       the  LAMHOME  environment variable, and instead advocates simply setting the PATH properly
       to switch between multiple LAM/MPI implementations.

NOTES

       Previous versions of LAM encouraged the use of hf77 to  compile  LAM  and/or  MPI  Fortran
       applications.   In  very  old versions of LAM, hf77 did not automatically add -lmpi to the
       command line.  hf77 was eventually deprecated and replaced with  mpif77.   The  executable
       hf77  is  now  simply a symbolic link to mpif77 just in case there's anyone out there that
       still uses that name.  It should be harmless to  pass  in  the  additional  -lmpi;  mpif77
       should silently do the Right Thing (only link in the MPI library once).

SEE ALSO

       f77(1), ld(1), lam-helpfile(5), mpicc(1)