Command line arguments

Any script that loads magnum.fd using the ‘import magnum’ command is subject to these command line arguments:

Usage: <your script>.py [options]

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit

  Hardware options:
    Options that control which hardware is used.

    -g GPU_ID           enable GPU processing (using 32-bit accuracy) on cuda
                        device GPU_ID. The simulator will fall back to CPU
                        mode if it was not compiled with CUDA support or when
                        no CUDA capable graphics cards were detected.
    -G GPU_ID           enable GPU processing (using 64-bit accuracy) on cuda
                        device GPU_ID. TODO: Describe fallback behaviour.
    -t NUM_THREADS, --threads=NUM_THREADS
                        enable CPU multithreading with NUM_THREADS (1..64)
                        threads. This parameter instructs the fftw library to
                        use NUM_THREADS threads for computing FFTs.

  Logging options:
    Options related to logging and benchmarking.

    -l LEVEL, --loglevel=LEVEL
                        set log level (0:Debug, 1:Info, 2:Warn, 4:Error,
                        5:Critical), default is Debug (0).
    --prof              Log profiling info at program exit.

  Parameter sweep options:
    These options have only an effect when the simulation script uses a
    Controller object to sweep through a parameter range.

    -p RANGE, --param-range=RANGE
                        set parameter range to run, e.g. --prange=0,64.
    --print-num-params  print number of sweep parameters to stdout and exit.
    --print-all-params  print all sweep parameters to stdout and exit.

  Miscellanous options:
    --on_io_error=MODE  Specifies what to do when an i/o error occurs when
                        writing an .omf/.vtk file. 0: Abort (default), 1:
                        Retry a few times, then abort, 2: Retry a few times,
                        then pause and ask for user intervention

Tweaks

Some tweaks can be definging certain environment variables before running a script. These are mostly useful for debugging and benchmarking the simulator.

• MAGNUM_DEMAG_GARBAGE

  Don’t calculate demag tensor (and thus produce invalid results). Useful for benchmarking only.

• MAGNUM_DEMAG_NO_INFINITY_CORRECTION

  Disable demag tensor infinity correction in case of periodic boundary conditions.

• MAGNUM_OMF_NOSCALE

  Always use “valuemultiplier=1” for writing .omf/.ohf files.

Example 1:

export MAGNUM_OMF_NOSCALE=1 && ./myscript.py

Example 2: (Inside Python script)

import sys; sys.environ["MAGNUM_OMF_NOSCALE"] = "1"
from magnum import *
# do stuff