/*D

    mpif77 - Compiles and links MPI programs written in Fortran 77

    Description:

    This command can be used to compile and link MPI programs written in

    Fortran.  It provides the options and any special libraries that are

    needed to compile and link MPI programs.  

    It is important to use this command, particularly when linking programs, 

    as it provides the necessary libraries.  

    Command line arguments:

+  \-show      - Show the commands that would be used without

                running them

.  \-help      - Give short help

.  \-f77=name   - Use compiler 'name' instead of the default choice.  Use

                this only if the compiler is compatible with the MPICH

                library (see below)

.  \-config=name - Load a configuration file for a particular compiler.

                This allows a single 'mpif77' command to be used with 

                multiple compilers.

.  \-compile_info - Show the steps for compiling a program.  This option

                can be used to see what options and include paths are

		used by mpif77.

.  \-link_info - Show the steps for linking a program.  This option

                can be used to see what options and libraries are used by

                mpif77.

.  \-profile=name - Use the MPI profiling given by name.  See below for

                details

.  \-echo      - Show exactly what this program is doing.

                This option should normally not be used.

.  \-static-mpi - Use a statically compile MPI library, but shared libraries

                for all of the other dependencies.

-  others     - are passed to the compiler or linker.  For example, '\-c'

                causes files to be compiled, '\-g' selects compilation with

                debugging on most systems, and '\-o name' causes linking

                with the output executable given the name 'name'.

    Environment Variables:

    The environment variables 'MPICH_F77' may be used

    to select different Fortran compiler and linker.  Note that since

    MPICH is built with a particular C and Fortran compiler, change the

    compilers used can cause problems.  Use this only if you could intermix

    code compiled with the different compilers.

    Compatible Compilers:

    The MPI library may be used with any compiler that uses the same 

    lengths for basic data objects (such as 'long double') and that 

    uses compatible run-time libraries.  On many systems, the various

    compilers are compatible and may be used interchangably.  There are 

    exceptions; if you use the 'MPICH_F77' environment variable or the 

    '\-f77=name' command-line argument to override the choice of compiler

    and encounter problems, try reconfiguring MPICH with the new compiler 

    and installing MPICH in a separate location.  See the installation manual 

    for more details.

    Examples:

To compile a single file 'foo.f', use

.vb

   mpif77 -c foo.f

.ve

To link the output and make an executable, use

.vb

   mpif77 -o foo foo.o

.ve

Combining compilation and linking in a single command

.vb

   mpif77 -o foo foo.f

.ve

is a convenient way to build simple programs.

 Selecting a Profiling Library:

 The '\-profile=name' argument allows you to specify an MPI profiling

 library to be used.  'name' can have two forms\:

.n A library in the same directory as the MPI library 

.n The name of a profile configuration file

.n

 If 'name' is a library, then this library is included before the MPI 

 library.  This allows the simple use of libraries that make use of the

 MPI profiling interface and that are installed in the same directory as 

 the MPI library.

 If 'name.conf' is the name of a file in the sysconfdir directory, then this

 is read and may define the following variables\:

+ PROFILE_PRELIB - Libraries (and paths) to include before the MPI library

. PROFILE_POSTLIB - Libraries to include after the MPI library

- PROFILE_INCPATHS - C preprocessor arguments for any include files

 For example, to add '/usr/local/myprof/include' to the include path and

 the library 'libmyprof.a' in '/usr/local/myprof/lib' to the link step, 

 you could create the file 'myprof.conf' with the lines

.vb

    PROFILE_PRELIB="-L/usr/local/myprof/lib -lmyprof"

    PROFILE_INCPATHS="-I/usr/local/myprof/include"

.ve

 and place it in the sysconfdir directory (this directory is set at

 configure time when MPICH is built).  Then using the command-line 

 argument '\-profile=myprof' will cause these

 definitions to be added to the relevant compile commands.

.seealso: mpicc, mpicxx, mpifort, mpiexec

D*/