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The Portable Extensible Toolkit for Scientific Computation (PETSc) package is a suite of data structures and routines for the scalable (parallel) solution of scientific applications modeled by partial differential equations. It is available from:

At the time of this writing, the version of PETSc available is 2.0.24, patch level 9 (be sure to download and install the patchfile).

The installation instructions (available from that web site) describes how to build PETSc, so we won't repeat much of it here (especially since it might change in future versions). These instructions only pertain to making LAM work correctly with PETSc.

  1. You need to manually edit the file bmake/${PETSC_ARCH}/ and set the following values:

    # These can both be blank (in terms of LAM 
    # options); LAM's wrapper
    # compilers take care of all of this for 
    # you.  LAM 6.2b users, however, will 
    # need to put "-lmpi" in the "*LINKER"
    # macros (below) if you use "hcc" instead 
    # of "mpicc".  PETSc, however, can use 
    # the -D flag shown below.
    MPI_LIB		=
    # For PETSc version 2.0.24 and below
    # For PETSc versions above 2.0.24
    # Use the "mpirun.lam" that is provided with
    # PETSc.  It is a short shell script that
    # invokes LAM's mpirun, but does some argument
    # parsing first.
    MPIRUN		= ${PETSC_DIR}/bin/mpirun.lam

  2. Additionally, you need to manually edit the file bmake/${PETSC_ARCH}/base_variables and set the following values:

    # You can also use "hcc" here, but LAM 6.2
    # users will need to specify "-lmpi" in the 
    # "MPI_LIBS" macro  You may need to 
    # specify the full path to mpicc if it isn't 
    # already in your path.  Same goes for "hf77"
    # and "hcp".  Also adjust the linker flags 
    # as necessary for your underlying compiler.
    C_CC        = mpicc 
    C_FC        = mpif77
    C_CLINKER   = mpicc ${COPTFLAGS} ..whatever flags you need..
    C_FLINKER   = mpif77 ${COPTFLAGS} ..whatever flags you need..
    C_CCV       = mpicc ..whatever flags you need..
    CXX_CC      = mpiCC 
    CXX_FC      = mpif77
    CXX_CLINKER = mpiCC ${COPTFLAGS} ..whatever flags you need..
    CXX_FLINKER = mpiCC ${COPTFLAGS} ..whatever flags you need..
    CXX_CCV     = mpiCC ..whatever flags you need..

  3. Finally, you will need to edit bin/mpirun.lam. You may need to set the full path to mpirun in the last line of this script. You can probably leave all the other options as they are (the -D option is somewhat useless when paired with the -s option, and will not work as expected if the -s option is removed and the PETSc executables are not in your $PATH, so it was removed from the example below).

    If you have a common filesystem between your nodes, you can remove the "-s n0" - it will save a few seconds on each program invocation. We also recommend that you add a "lamclean" after the mpirun line, to ensure that no messages are left around on the network after each example application finishes.

    # Include the full path to mpirun and lamclean
    # if they are not already in your $PATH.
    /path/to/mpirun -w -c $np -s n0 $proname -- $options

The remainder of the values are fairly obvious and irrelevant to LAM (i.e., if you don't see it here, specific values not necessary for LAM); you can set whatever optimization level you want, etc.

If you follow the rest of the instructions for building, PETSc will build correctly and use LAM as its MPI communication layer.