Install

To install the Gadget2, you need to install MPI, fftw2, gsl and hdf5. Here I install all of these by compiling the source code. To avoiding mixing with the system's library, I put all these in a specified folder, and the structure is

/Users/wangk/Documents/Project/library/
├── bin
├── etc
├── include
├── lib
├── libsource
└── share

where the libsource is for the source code.

Another thing is that the default c/c++ compiler on Mac is clang/clang++, but I prefer gcc/g++. So I install gcc/g++ using Homebrew. In the following content, I will redirect the c/c++ compiler to gcc/g++.

Open MPI

I chose Open MPI instead of MPICH because the later does not work on my computer after installing. You can download it from Here. There are three steps to install

./configure \
    CC=/usr/local/bin/gcc-9 \
    CXX=/usr/local/bin/g++-9 \
    --prefix=/Users/wangk/Documents/Project/library
make
make install

Here CC should link to the executable gcc and CXX should be executable g++. The --prefix is tell the installing program where to put the products(it will put the header file in /location_of_prefix/include/, the library in /location_of_prefix/lib/ and executable in /location_of_prefix/bin/)

It will take a while to install Open MPI, since it is a big program.

FFTW2

Gadget2 requires fftw2, and you can download it from here.

./configure \
    CC=/usr/local/bin/gcc-9 \
    --includedir=/Users/wangk/Documents/Project/library/include/fftw2 \
    --libdir=/Users/wangk/Documents/Project/library/lib/fftw2 \
    --enable-mpi \
    --enable-type-prefix \
    MPICC=/Users/wangk/Documents/Project/library/bin/mpicc
make
make install
make clean
./configure \
    CC=/usr/local/bin/gcc-9 \
    --includedir=/Users/wangk/Documents/Project/library/include/fftw2 \
    --libdir=/Users/wangk/Documents/Project/library/lib/fftw2 \
    --enable-mpi \
    --enable-float \
    --enable-type-prefix \
    MPICC=/Users/wangk/Documents/Project/library/bin/mpicc
make
make install

There are several tricky things here.

1. Gadget2 needs fftw2, but the newest is fftw3. Since I do not want to mess them up, I specify the include path and lib separately using --includedir and --libdir. And fftw will not generate anything in etc/ and share/, so I do not need to specify their directory.

2. There are two kinds of precision for fftw, single and double. --enable-type-prefix is telling the installing program to distinguish them by adding a character, then you can install both the single version and the double version, separately. After the above installation, you can see the header file in location_of_prefix/include/fftw2/ as

    dfftw.h  dfftw_mpi.h  drfftw.h  drfftw_mpi.h
    sfftw.h  sfftw_mpi.h  srfftw.h  srfftw_mpi.h

   The first installation will install the double version by default, and the second is for single precision, where you need to --enable-float. Also, you need to make clean before the second installation. By the way, when you choose to enable type prefix, you can not #include <fftw.h> in your program, you need #include <sfftw.h> or #include <dfftw.h> to specify the precision. Also, you need change -lfftw to -lsfftw or -ldfftw when you are compiling the program.

3. You need to enable the MPI for fftw, so you need to specify the path the mpi executable, which, in my case, is MPICC=/Users/wangk/Documents/Project/library/bin/mpicc

GSL

You can download it from Here. The installation is easy.

./configure \
    CC=/usr/local/bin/gcc-9 \
    CXX=/usr/local/bin/g++-9 \
    --prefix=/Users/wangk/Documents/Project/library
make
make install

HDF5

You can download the source code Here

./configure \
    CC=/Users/wangk/Documents/Project/library/bin/mpicc \
    CXX=/usr/local/bin/g++-9 \
    --includedir=/Users/wangk/Documents/Project/library/include/hdf5 \
    --libdir=/Users/wangk/Documents/Project/library/lib/hdf5 \
    --enable-cxx
make
make install

There are several thing need to be noted

1. If you need the c++ interface, you need to --enable-cxx and you need to specify the c++ compiler, which in my case is CXX=/usr/local/bin/g++-9.
2. You cannot specify --enable-cxx and --enable-parallel simultaneously. Since I will not use the parallel IO, so I just enable c++ interface.

Gadget2

After installing all the required package, it becomes quiet easy to install Gadget2, where you can download it from here.

I uncommented or modified the following things. (It works, but I am not sure if they are necessary, you should read the manual)

OPT += -DDOUBLEPRECISION_FFTW

CC = /Users/wangk/Documents/Project/library/bin/mpicc # sets the C-compiler
OPTIMIZE =  -O3 -Wall -g -DH5_USE_16_API # sets optimization and warning flags

SYSTYPE="KAI"

ifeq ($(SYSTYPE),"KAI")
CC       =  /Users/wangk/Documents/Project/library/bin/mpicc
OPTIMIZE =  -O3 -Wall -DH5_USE_16_API
GSL_INCL =  -I/Users/wangk/Documents/Project/library/include
GSL_LIBS =  -L/Users/wangk/Documents/Project/library/lib
FFTW_INCL=  -I/Users/wangk/Documents/Project/library/include/fftw2
FFTW_LIBS=  -L/Users/wangk/Documents/Project/library/lib/fftw2
MPICHLIB =  -L/Users/wangk/Documents/Project/library/lib
HDF5INCL =  -I/Users/wangk/Documents/Project/library/include/hdf5
HDF5LIB  =  -L/Users/wangk/Documents/Project/library/lib/hdf5 -lhdf5 -lz
endif

Then, you can run Gadget2 using the provided example and initial condition. Have fun!