Building and Running RMHD2D: 1. Edit one of the machine-dependent Makefiles, e.g. Make.reynolds-linux, to set up the various compilers, compiler flags, libraries, and Fortran-to-C translation directives. NOTE: this version of the code is designed to interface with sundials versions 2.4.0 or 2.5.0, although it may work with older/newer versions as well. However, for versions <= 2.3.0, when installing sundials you must ensure that the source code file sundials-2.x.0/include/sundials/sundials_fnvector.h is copied to the installation directory. Unfortunately, this is not the default behavior when building/installing in a different directory than where it is installed. 2. Link this machine-dependent Makefile to Make.machine: e.g. ln -fs Make.reynolds-linux Make.machine 3. Edit one of the problem configuration makefiles, e.g. Make.config-KH, to set up the appropriate dimensionality (2D vs 2.5D), boundary conditions, flux discretization choices, parallelism, and preconditioning for the type of problem that you wish to run. 4. Link this problem-dependent Makefile to Make.config: e.g. ln -s Make.config-KH Make.config 5. Type 'make <target>', where <target> specifies the type of executable (problem type and time integration algorithm) that you wish to build. Typing 'make' alone will bring up a list of possible targets. 6. Copy problem-specific input files to the run-time directory from the ./inputs directory. You will need the files mhd.inp, prop.inp and mesh.inp for all problems (remove the problem specifier suffix from the file name). For some problems, you will also need the problem-specific input parameter files provided in this directory, e.g. the Kelvin-Helmholtz problem requires kh_init.inp. If the time-integration algorithm is KINSOL, you will also need kincontrol.inp; if it is CVODE, you will need cvcontrol.inp. 7. Edit the input files to your tastes and run your executable. * To set the problem size and parallelism topology, edit the mesh.inp file to set the problem size (nx, ny and nz give the total problem dimensions) along with the parallelism topology information (xprocs, yprocs and zprocs give the number of processors in each Cartesian dimension).