Branson

Introduction

So you've decided to use Branson...

Here are some things to know:

• Branson is not an acronym.
• The point of Branson is to study different algorithms for parallel Monte Carlo transport. Currently it contains particle passing and mesh passing methods for domain decomposition.
• Many of the parameters that impact parallel performance can be set in the input file.
• The input file format is ugly right now and I don't have a good list of parameters and what they do. Sorry.
• Input files are in XML, which makes them easy to generate and change in python.
• Input files are complicated when you want to have multiple spatial regions but are pretty simple otherwise.

How to install

Accessing the sources

• Download a tarball from Github, or
• Fork and clone the git repository.

# after forking the repository
git clone git@github.com:[github-username]/branson
cd branson
git remote add upstream git@github.com:lanl/branson
git checkout -b develop upstream/develop

Installing Branson:

• Build requirements:
  • C/C++ compiler(s) with support for C11 and C++14.
  • CMake 3.9+
  • MPI 3.0+ (OpenMPI 1.10+, mpich, etc.)
  • Metis
• Optional dependencies (needed for visualization)
  • HDF5
  • Silo
  • If these tools aren't readily avilable on your target machine, consider using a package manager like spack to help you install these tools.
• There is only one CMake user option right now: CMAKE_BUILD_TYPE which can be set on the command line with -DCMAKE_BUILD_TYPE=<Debug|Release> and the default is Release.
• If cmake has trouble finding your installed TPLs, you can try
  • appending their locations to CMAKE_PREFIX_PATH,
  • Setting helper variables like HDF5_ROOT (refer to the cmake documentation or the FindXXX.cmake scripts in Branson's src/config directory for a list of variables), or
  • try running ccmake . from the build directory and changing the values of build system variables related to TPL locations.

EXPORT CXX=`which g++`
cd $build_dir
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=<install-location> ${branson_source_dir}/src
make -j

Testing the build:

cd $build_dir
ctest -j 32

Special builds

Fake Multigrop Branson:

• The clean_mg branch has a new capability that mimics the data flow in real multigroup transport.
• This branch sets the number of groups at the configure step in CMake. I know this is messy from a usability standpoint but it makes the data layout very easy to control when the number of groups is known at compile time. Use the N_GROUPS CMake variable to set the number of groups (e.g. cmake -DN_GROUPS=10 ../path/to/CMakeLists.txt).
• The code will still produce gray results! The physical value in each group is the same and it's still set via the input deck.
• This branch samples a group with a uniform PDF (it does not weight the opacity with a Planckian spectrum).

Authors

• Branson was written by Alex R. Long
• Random123 is by D. E. Shaw Research, Copyright 2010-2011
• PugiXML is by zeux (Arseny Kapoulkine), MIT License
• RNG.h uses code from Draco

Release

Branson is released under the BSD 3-Clause License. For more details see the LICENSE.md file.

LANL code designation: C17048