Configuration - ALF — Algorithms for Lattice Fermions

Options for configure.sh and the ALF build system.

configure.sh Usage¶

source configure.sh <MACHINE> [MODE] [STAB] [options...]

You must source (not execute) this script — it sets environment variables that the Makefile reads. Arguments are case-insensitive and order-independent (except MACHINE must come first or be the only positional argument).

Machine / Compiler¶

MACHINE	Compiler	Linear Algebra	Notes
`GNU`	`gfortran` / `mpifort`	`-llapack -lblas`	Most common for local builds
`Intel`	`ifort` / `mpiifort`	MKL (`-qmkl` or `-mkl`)	Classic Intel Fortran
`IntelLLVM` or `IntelX`	`ifx` / `mpiifort -fc=ifx`	MKL (`-qmkl`)	New LLVM-based Intel Fortran
`PGI`	`pgfortran` / `mpifort`	`-llapack -lblas`	NVIDIA/PGI compilers
`SuperMUC-NG`	`mpiifort`	MKL	Auto-loads LRZ modules
`JUWELS`	`mpiifort`	MKL	Auto-loads JSC modules
`FRITZ`	Intel (auto-detected)	MKL	Auto-loads NHR@FAU modules

If MACHINE is unrecognized, ALF falls back to gfortran serial mode.

Build Mode¶

MODE	Preprocessor Flags	Description
`MPI` (default)	`-DMPI`	MPI parallelization across bins
`noMPI`	(none)	Serial execution
`Tempering`	`-DMPI -DTEMPERING`	Parallel tempering (requires MPI)
`PP` or `PARALLEL_PARAMS`	`-DMPI -DTEMPERING -DPARALLEL_PARAMS`	Parallel runs with different parameters (requires MPI)

Stabilization Scheme¶

STAB	Flag	Description
(default)	(none)	Standard stabilization
`STAB1`	`-DSTAB1`	Older UDV decomposition
`STAB2`	`-DSTAB2`	UDV with additional normalizations
`STAB3`	`-DSTAB3`	Newest: separates large and small scales
`LOG`	`-DSTABLOG`	Log storage for internal scales — extends accessible parameter ranges ( $\beta$ , interaction strength)

See [[Stabilization Parameters]] for guidance on choosing a scheme.

Optional Flags¶

Flag	Effect
`HDF5`	Enable HDF5 output. ALF auto-installs HDF5 locally if not yet built for the current compiler.
`Devel`	Enable development/debug flags: warnings, bounds checking, backtraces
`NO-INTERACTIVE`	Suppress interactive prompts (e.g., auto-accept HDF5 download). Useful in scripts.
`NO-FALLBACK`	Return error instead of falling back to serial gfortran for unknown machines

Custom Compiler Flags¶

To pass additional flags to the compiler:

export ALF_FLAGS_EXT="-my-flag"
source configure.sh GNU MPI

Custom HDF5 Directory¶

By default, ALF installs HDF5 into ALF/HDF5/<compiler_version>/. To override:

export ALF_HDF5_DIR=/path/to/custom/hdf5
source configure.sh GNU MPI HDF5

Environment Variables Set by configure.sh¶

After sourcing, these are exported and used by make:

Variable	Purpose
`ALF_DIR`	Root directory of ALF
`ALF_FC`	Fortran compiler command
`ALF_FLAGS_PROG`	Compiler flags for the main program
`ALF_FLAGS_MODULES`	Compiler flags for library modules
`ALF_FLAGS_ANA`	Compiler flags for analysis tools
`ALF_FLAGS_QRREF`	Compiler flags for QR library
`ALF_LIB`	Linker flags (libraries)

Compiler-Specific Notes¶

GNU (gfortran)¶

Default optimization: -O3 -ffast-math -ffree-line-length-none
OpenMP enabled by default (-fopenmp)
Devel mode adds: -Wconversion -Werror -fcheck=all -g -fbacktrace

Intel Classic (ifort)¶

Default optimization: -O3 -fp-model fast=2 -xHost -ipo -ip
OpenMP enabled (-parallel -qopenmp)
Devel mode adds: -warn all -check all -g -traceback

Intel LLVM (ifx)¶

Default optimization: -O3 -fp-model=fast=2 -xHost
OpenMP not enabled by default (can be uncommented in configure.sh)
Devel mode adds: -warn all -check all,nouninit -g -traceback

Common Recipes¶

# Local development (serial, debug checks, fast iteration)
source configure.sh GNU noMPI devel

# Production run (MPI + HDF5)
source configure.sh GNU MPI HDF5

# Parallel tempering
source configure.sh GNU Tempering HDF5

# Non-interactive (CI/scripting)
source configure.sh GNU MPI HDF5 NO-INTERACTIVE