Ready-to-use Kwant packages are available for many platforms (like GNU/Linux, Mac OS X, Microsoft Windows). See the installation page of the Kwant website for instructions on how to install Kwant on your platform. This is the recommended way for new users.
The remainder of this section documents how to build Kwant from source. This information is mostly of interest to contributors and packagers.
In addition, to build a copy of Kwant that has been checked-out directly from version control, you will also need Cython 0.22 or newer. You do not need Cython to build Kwant that has been unpacked from a source .tar.gz-file.
Kwant can be built and installed following the usual Python conventions by running the following commands in the root directory of the Kwant distribution.
python setup.py build
python setup.py install
Depending on your system, you might have to run the second command with
administrator privileges (e.g. prefixing it with sudo).
After installation, tests can be run with:
python -c 'import kwant; kwant.test()'
The tutorial examples can be found in the directory tutorial inside the root
directory of the Kwant source distribution.
(Cython will be run automatically when the source tree has been checked out of
version control. Kwant tarballs include the Cython-generated files, and
cythonization is disabled when building not from git. If ever necessary, this
default can be overridden by giving the --cython option to setup.py.)
The setup script of Kwant has to know how to link against LAPACK & BLAS, and,
optionally, MUMPS. By default it will assume that LAPACK and BLAS can be found
under their usual names. MUMPS will be not linked against by default, except
on Debian-based systems when the package libmumps-scotch-dev is installed.
All these settings can be configured by creating/editing the file
build.conf in the root directory of the Kwant distribution. This
configuration file consists of sections, one for each dependency, led by a
[dependency-name] header and followed by name = value entries. Possible names
are keyword arguments for distutils.core.Extension (For a complete list,
see its documentation).
The corresponding values are whitespace-separated lists of strings.
The two currently possible sections are [lapack] and [mumps]. The former configures the linking against LAPACK _AND_ BLAS, the latter against MUMPS (without LAPACK and BLAS).
Example build.conf for linking Kwant against a self-compiled MUMPS, SCOTCH and METIS:
[mumps]
libraries = zmumps mumps_common pord metis esmumps scotch scotcherr mpiseq gfortran
Example build.conf for linking Kwant with Intel MKL.:
[lapack]
libraries = mkl_intel_lp64 mkl_sequential mkl_core mkl_def
library_dirs = /opt/intel/mkl/lib/intel64
extra_link_args = -Wl,-rpath=/opt/intel/mkl/lib/intel64
The detailed syntax of build.conf is explained in the documentation of
Python’s configparser module.
To build the documentation, the Sphinx documentation generator is required with numpydoc extension
(version 0.5 or newer). If PDF documentation is to be built, the tools
from the libRSVG (Debian/Ubuntu package
librsvg2-bin) are needed to convert SVG drawings into the PDF format.
As a prerequisite for building the documentation, Kwant must have been built
successfully using python setup.py build as described above (or Kwant must
be already installed in Python’s search path). HTML documentation is built by
entering the doc subdirectory of the Kwant package and executing make
html. PDF documentation is generated by executing make latex followed
by make all-pdf in doc/build/latex.
Because of some quirks of how Sphinx works, it might be necessary to execute
make clean between building HTML and PDF documentation. If this is not
done, Sphinx may mistakenly use PNG files for PDF output or other problems may
appear.
Kwant should run on all recent Unix-like systems. The following instructions
have been verified to work on Debian 8 (Jessie) or newer, and on Ubuntu 14.04 or
newer. For other distributions step 1 will likely have to be adapted. If
Ubuntu-style sudo is not available, the respective command must be run as
root.
Install the required packages. On Debian-based systems like Ubuntu this can be done by running the command
sudo apt-get install python-dev python-scipy python-matplotlib python-nose g++ gfortran libopenblas-dev liblapack-dev libmumps-scotch-dev
Unpack Tinyarray, enter its directory. To build and install, run
python setup.py build
sudo python setup.py install
Inside the Kwant source distribution’s root directory run
python setup.py build
sudo python setup.py install
By default the package will be installed under /usr/local. Run python
setup.py --help install for installation options.
The required dependencies of Kwant are best installed with one of the packaging systems. Here we only consider the case of MacPorts in detail. Some remarks for homebrew are given below.
Install a recent version of MacPorts, as explained in the installation instructions of MacPorts. The MacPorts section of the Kwant website may be also of interest. (Note that it describes how to install Kwant using a ports file, while the aim here is to install from source manually.)
Install the required dependencies:
sudo port install gcc47 python27 py27-numpy py27-scipy py27-matplotlib mumps_seq
sudo port select --set python python27
Unpack Tinyarray, enter its directory, build and install:
python setup.py build
sudo python setup.py install
Unpack Kwant, go to the Kwant directory, and edit build.conf to read:
[lapack]
extra_link_args = -Wl,-framework -Wl,Accelerate
[mumps]
include_dirs = /opt/local/include
library_dirs = /opt/local/lib
libraries = zmumps_seq mumps_common_seq pord_seq esmumps scotch scotcherr mpiseq gfortran
Then, build and install Kwant.
CC=gcc-mp-4.7 LDSHARED='gcc-mp-4.7 -shared -undefined dynamic_lookup' python setup.py build
sudo python setup.py install
You might note that installing Kwant on Mac OS X is somewhat more involved than
installing on Linux. Part of the reason is that we need to mix Fortran and C
code in Kwant: While C code is usually compiled using Apple compilers,
Fortran code must be compiled with the Gnu Fortran compiler (there is
no Apple Fortran compiler). For this reason we force the Gnu compiler suite
with the environment variables CC and LDSHARED as shown above.
It is also possible to build Kwant using homebrew. The dependencies can be installed as
brew install gcc python
brew tap homebrew/science
brew tap homebrew/python
brew tap kwant-project/kwant
pip install nose six
brew install numpy scipy matplotlib
Note that during the installation you will be told which paths to add when you want to compile/link against scotch/metis/mumps; you need to add these to the build.conf file. Also, when linking against MUMPS, one needs also to link against METIS (in addition to the libraries needed for MacPorts).
Our efforts to compile Kwant on Windows using only free software (MinGW) were only moderately successful. At the end of a very complicated process we obtained packages that worked, albeit unreliably. As the only recommended way to compile Python extensions on Windows is using Visual C++, it may well be that there exists no easy solution.
It is possible to compile Kwant on Windows using non-free compilers, however we (the authors of Kwant) have no experience with this. The existing Windows binary installers of Kwant and Tinyarray were kindly prepared by Christoph Gohlke.