FORTRAN_COMP

FORTRAN_COMP defines the fortran compile statement that will be used to compile the non-precompiled parts of the TensErLEED program. Statements that go after the file name can be added with the post flag.

The structure search can use mpirun for parallelization. This is optional, but highly recommended. If you use MPI you require an MPI compiler. If mpiifort or mpifort are present, they will be used automatically. Optimization can be customized with the mpi flag. If mpiifort/mpifort or mpirun are not found on the system, the search will be compiled with the standard FORTRAN_COMP compiler and executed without parallelization.

See the installation section for details on how to install the the Fortran compilers, the MPI wrappers and mpirun.

Default: if ifort is present:

FORTRAN_COMP = 'ifort -O2 -I/opt/intel/mkl/include'
FORTRAN_COMP post = '-L/opt/intel/mkl/lib/intel64 -lmkl_intel_lp64 -lmkl_intel_thread -lmkl_core -liomp5 -lpthread -lm -ldl -traceback'

FORTRAN_COMP = 'ifort /O2 /I"%MKLROOT%/include"'
FORTRAN_COMP post = '/Qmkl:parallel /traceback'

Where %MKLROOT% is the path that is automatically set as an environment variable by Intel oneAPI® when it is initialized.

if ifort is not present, but gfortran is:

FORTRAN_COMP = 'gfortran -O2'
FORTRAN_COMP post = '-llapack -lpthread -lblas -fbacktrace'

Additionally, if mpirun or, on Windows, mpiexec are present:

FORTRAN_COMP mpi = 'mpiifort -Ofast'

FORTRAN_COMP mpi = 'cmd mpiifort /Ofast'

On Windows, mpiifort is a .bat file, not an executable. Python’s subprocess cannot directly run it. This is why it is prepended by cmd (i.e., the Windows Command Prompt).

Or, if mpiifort is not present, but mpifort is:

FORTRAN_COMP mpi = 'mpifort -Ofast -fallow-argument-mismatch'

Warning

If you are using an older version of gfortran packaged with GCC 9 or earlier, you need to remove the compiler flag -fallow-argument-mismatch. viperleed.calc should do this automatically if it can detect the compiler version. Should this fail, you can explicitly specify in PARAMETERS:

FORTRAN_COMP mpi = 'mpifort -Ofast'

This is necessary, because type-checks were made stricter in GCC 10, making -fallow-argument-mismatch mandatory to compile unaltered TensErLEED. However, earlier versions of GCC and gfortran may not recognize the flag.

Changed in version 0.14.1: Added correct defaults for ifort/mpiifort on Windows. On earlier versions, Windows users needed to manually set FORTRAN_COMP.

Syntax:

FORTRAN_COMP = 'ifort -O3 -I/opt/intel/mkl/include'
FORTRAN_COMP post = '-L/opt/intel/mkl/lib/intel64 -lmkl_intel_lp64 -lmkl_intel_thread -lmkl_core -liomp5 -lpthread -lm -ldl'
FORTRAN_COMP mpi = 'mpiifort -O2'

OR

FORTRAN_COMP = ifort
FORTRAN_COMP = gfortran
FORTRAN_COMP mpi = mpifort
FORTRAN_COMP mpi = mpiifort

Acceptable values: Either ifort or gfortran (or mpifort/mpiifort for FORTRAN_COMP mpi) (this will add the default flags listed above for both FORTRAN_COMP and FORTRAN_COMP post), or a string containing the full compile statement, including optimization flags, libraries, etc. Quotation marks are optional and will be stripped from the string.

This compile statement will be used for all Fortran code compiled while the program runs. Any optimization statements should be included in the string. Needless to say, the Fortran compiler needs to be installed on the computer that executes the script.

Whether the default flags work depends not only on the ifort or gfortran packages being present, but also on additional packages and the local library structure. Therefore, explicitly declaring FORTRAN_COMP and FORTRAN_COMP post as strings is generally preferable.

Note

  • mpifort: mpifort is only a “wrapper” compiler, which effectively calls an underlying back-end fortran compiler (usually gfortran) with a number of flags suitable for mpi scripts. If there are problems or you want to see exactly what mpifort is doing, use mpifort -showme to see what the mpifort command will be interpreted as (see also the mpifort man page). If this does not work well, you may want to try replacing the FORTRAN_COMP mpi = mpifort with the output of the -showme command as an explicit string, fixing paths if necessary.

  • mpifort: if compiling with mpifort causes an error like Symbol `time' causes overflow in R_X86_64_PC32 relocation in the search log (use LOG_SEARCH to produce such a log), this can be resolved by using mpifort with the additional flag -no-pie.

Warning

  • gfortran/mpifort: When using aggressive (-Ofast) optimization flags, checks for NaNs and +/-Inf values are disabled by the compiler. This poses no known problems for TensErLEED up to at least v.1.7.3, but it could lead to unexpected behavior in the future. Use the flag -fno-finite-math-only to re-enable these checks.