# PT-Scotch¶

PT-Scotch can be used to replace ParMETIS. (We prefer ParMETIS since this is the default for SuperLU_DIST)

Note

PT-Scotch 6.0.5 seems to be incompatible with PEXSI. For the moment please use 6.0.0 (contributed by Victor Yu, 6/20/2018)

Follow the installation step to install PT-Scotch. In INSTALL.TXT, pay special attention to the following sections in order to compile PT-Scotch correctly.

2.3) Integer size issues

PT-Scotch is also METIS-Compatible. See the following section in INSTALL.TXT for more information.

2.9) MeTiS compatibility library
In src/ directory, you need ::
make ptscotch

to compile PT-Scotch.

Note

Just typing make will generate the Scotch library but not PT-Scotch. Then all libraries will be given in lib/ directory.**

# symPACK¶

symPACK can be used to replace SuperLU_DIST (for $$LDL^T$$ factorization but not $$LU$$ factorization)

symPACK is a sparse symmetric matrix direct linear solver. More information can be found at http://www.sympack.org/.

git clone https://github.com/symPACK/symPACK.git /path/to/sympack

Several environment variables can be set before configuring the build:

SCOTCH_DIR = Installation directory for SCOTCH and PT-SCOTCH

Then, create a build directory, enter that directory and type:

cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/path/to/install/sympack ...OPTIONS... /path/to/sympack


The ...OPTIONS... can be one of the following:

• -DENABLE_METIS=ON|OFF to make METIS ordering available in symPACK (METIS_DIR must be set in the environment)
• -DENABLE_PARMETIS=ON|OFF to make ParMETIS ordering available in symPACK (PARMETIS_DIR must be set in the environment, METIS_DIR is required as well)
• -DENABLE_SCOTCH=ON|OFF to make SCOTCH / PT-SCOTCH orderings available in symPACK (SCOTCH_DIR must be set in the environment)

Some platforms have preconfigured toolchain files which can be used by adding the following option to the cmake command (To build on NERSC Edison machine for instance):

-DCMAKE_TOOLCHAIN_FILE=/path/to/sympack/toolchains/edison.cmake


A sample toolchain file can be found in /path/to/sympack/toolchains/build_config.cmake and customized for the target platform.

The cmake command will configure the build process, which can now start by typing ::
make make install

Additionally, a standalone driver for symPACK can be built by typing make examples

Note

Since cmake also compiles UPCxx and GASNET, the compilation time may be long especially on certain clusters.

# Build PEXSI with the old Makefile system¶

Configuration of PEXSI is controlled by a single make.inc file. Examples of the make.inc file are given under the config/ directory.

Find make.inc with the most similar architecture, and copy to the main PEXSI directory (using Edison at NERSC for example, a CRAY X30 machine). ${PEXSI_DIR} stands for the main directory of PEXSI. cd${PEXSI_DIR}
cp config/make.inc.CRAY_XC30.intel make.inc


Edit the variables in make.inc.

PEXSI_DIR     = Main directory for PEXSI
DSUPERLU_DIR  = Main directory for SuperLU_DIST
PARMETIS_DIR  = Main directory for ParMETIS
PTSCOTCH_DIR  = Main directory for PT-Scotch


Edit the compiler options, for instance

CC           = cc
CXX          = CC
FC           = ftn


The USE_SYMPACK option can be set to use the symPACK solver in PEXSI. It is set to 0 by default. When set to 1, the SYMPACK_DIR variable must be pointing to symPACK’s installation directory.

Note

• Starting from PEXSI v0.8.0, -std=c++11 is required in CXXFLAGS.
• Starting from PEXSI v0.9.2, -std=c99 is required in CFLAGS to be compatible with SuperLU_DIST starting from v4.3.
• For FORTRAN users, CPP_LIB=-lstdc++ -lmpi -lmpi_cxx is often needed. Check this if there is link error.
• PEXSI can be compiled using debug or release mode in by the variable COMPILE_MODE in make.inc. This variable mainly controls the compiling flag -DRELEASE. The debug mode introduces tracing of call stacks at all levels of functions, and may significantly slow down the code. For production runs, use release mode.
• The USE_PROFILE option is for internal test purpose. Usually set this to 0.

The installation procedure and dependencies of every version of the PEXSI package may be different. Please follow the documentation of the version of the PEXSI package you are working with (provided in the Download Page )

If make.inc is configured correctly,:

make
make install


Should build the PEXSI library under the build directory ready to be used in an external package. If the FORTRAN interface is needed, type:

make finstall


If examples are needed (not necessary if you use PEXSI in an external package), type

make examples


which will generate C examples in examples/ directory and FORTRAN examples in fortran/ directory, respectively.:

make all


will make the library and the examples.