Compiling EPOCH

To compile EPOCH in the supplied state, you must first change to the correct working directory. As explained in , the root directory for EPOCH contains several subdirectories, including separate directories for each of the 1D, 2D and 3D versions of the code. To compile the 2D version of the code, you first switch to the “epoch2d” directory using the command cd $HOME/epoch/epoch2d and then type make and the code will compile. There are certain options within the code which are controlled by compiler preprocessors and are described in the next section. When the code is compiled, it creates a new directory called “bin” containing the compiled binary which will be called epoch1d, epoch2d or epoch3d. To run the code, just execute the binary file by typing: ./bin/epoch2d or whatever the correct binary is for the dimensionality of the code that you have. You should be given a screen which begins with the EPOCH logo, and then reads:

The code was compiled with no compile time options

Welcome to EPOCH2D version 4.12.0   (commit v4.12.0-0-gfd74a464-clean)

Code is running on 1 processing elements

Specify output directory

At this point, the user simply types in the name of the (already existing) output directory and the code will read the input deck files inside the specified directory and start running. To run the code in parallel, just use the normal mpirun or mpiexec scripts supplied by your MPI implementation. If you want the code to run unattended, then you will need to pipe in the output directory name to be used. The method for doing this varies between MPI implementations. For many MPI implementations (such as recent versions of OpenMPI) this can be achieved with the following: echo Data | mpirun -np 2 ./bin/epoch2d Some cluster setups accept the following instead: mpirun -np 2 ./bin/epoch2d < deck.file where “deck.file” is a file containing the name of the output directory. Some cluster queueing systems do not allow the use of input pipes to mpirun. In this case, there is usually a “-stdin” command line option to specify an input file. See your cluster documentation for more details.

As of version 4.2.12, EPOCH now checks for the existence of a file named “USE_DATA_DIRECTORY” in the current working directory before it prompts the user for a Data directory. If such a file exists, it reads it to obtain the name of the data directory to use and does not prompt the user. If no such file exists, it prompts for a data directory name as before. This is useful for cluster setups in which it is difficult or impossible to pipe in the directory name using a job script.

The “Makefile” contains configurations for fort, gfortran, pgi, g95, hector/archer and ibm (the compiler suite used on IBM’s BlueGene machines). In order to compile using one of the listed configurations, add the “COMPILER=” option to the “make” command. For example make COMPILER=gfortran will compile the code using the gfortran compiler and appropriate compiler flags. The options are

• COMPILER=gfortran - GNU Fortran
• COMPILER=intel - Intel ifort
• COMPILER=pgi - Portland group compiler
• COMPILER=g95 - G95 compiler
• COMPILER=ibm - IBM AIX Fortran compiler for BlueGene
• COMPILER=hector - Cray compiler as used on hector and archer

As of version 4.11, it is now possible for the build system to automatically detect the correct compiler to use. Typing make COMPILER=auto will cause the build system to guess which compiler is in use. Note that this might not always work, so it is better to use the correct value for COMPILER if it is already known.

You can also compile the code with debugging flags by adding “MODE=debug” and can compile using more than one processor by using “-j<n>”, where “<n>” is the number of processors to use. Note that this is just to speed up the compilation process; the resulting binary can be run on any number of processors.