GalSim is a python module that has much of its implementation in C++ for improved computational efficiency. GalSim supports both Python 2 and Python 3. It is regularly tested on Python versions (2.7, 3.6, 3.7, 3.8, 3.9).
System requirements: GalSim currently only supports Linux and Mac OSX. Possibly other POSIX-compliant systems, but we specifically do not currently support Windows.
WARNING: The GalSim 2.3.x release series will be the last to support Python 2.7, as it is currently past its end-of-life. Please migrate to Python 3 in order to be able to use future versions of GalSim.
The usual way to install GalSim is now (starting with version 2.0) simply:
pip install galsim
which will install the latest official release of GalSim.
Note that you may need to use sudo with the above command if you are installing into system directories. If you do not have write privileges for the directory it is trying to install into, you can use the --user flag to install into a local directory instead. (Normally something like $HOME/Library/Python/3.8 or $HOME/.local, depending on your system.)
If you would rather install from source (e.g. to work on a development branch), you can do:
git clone git@github.com:GalSim-developers/GalSim.git cd GalSim pip install -r requirements.txt pip install .
(again possibly with either sudo or --user).
Either of these installation methods should handle most of the required dependencies for you if you do not have them already installed on your machine. In particular, all of the python dependencies should be automatically installed for you.
FFTW is not directly pip installable, so if the above installation fails, you may need to install it separately. See the link below for details about how to do this.
For complete details, see:
http://galsim-developers.github.io/GalSim/_build/html/install_pip.html
Another option If you use Anaconda Python is to use conda:
conda install -c conda-forge galsim
The conda installation method will install all of the dependencies for you. But if you want more information, see:
http://galsim-developers.github.io/GalSim/_build/html/install_conda.html