Parallel Version.

AUTO contains code which allows it to run in on parallel computers. Namely, it can use either OpenMP to run most of its code in parallel on shared-memory multi-processors, or the MPI message passing library. When the configure script is run it will try to detect if the Fortran compiler supports OpenMP; examples are Gfortran 4.2 and the Intel Fortran Compiler. If it is successful the necessary compiler flags are used to enable OpenMP in AUTO . To force the configure script not to use OpenMP, one may type ./configure -without-openmp, and then type make. On the other hand, unless there is some particular difficulty, we recommend that that the configure script be used without arguments, since the parallel version of AUTO may easily be controlled, and even run in a serial mode, through the use of the environment variable OMP_NUM_THREADS.

For example, to run the AUTO executable auto.exe in serial mode you just type export OMP_NUM_THREADS=1. To run the same command in parallel on 4 processors you type export OMP_NUM_THREADS=4. Without any OMP_NUM_THREADS set the number of processors that AUTO will use can be equal to the actual number of processors on the system, or can be equal to one; this is system-dependent.

The MPI message passing library is not used by default. You can enable it by typing ./configure -with-mpi . If OpenMP and MPI are both used then AUTO uses mixed mode, with MPI parallelisation occurring at the top level.

Running the MPI version is somewhat more complex because of the fact that MPI normally uses some external program for starting the computational processes. The exact name and command line options of this external program depends on your MPI installation. A common name for this MPI external program is mpirun, and a common command line option which defines the number of computational processes is -np. Accordingly, if you wanted to run the MPI version of AUTO  on four processors, with the above external program, you would type mpirun -np 4 file.exe. Please see your local MPI documentation for more detail.