Installing GNU Scientific Library (GSL) and CythonGSL in Windows

Joon Ro

2015-05-25 00:50

1. Download
- 1.1. GSL
- 1.2. CythonGSL
2. Installing GSL
3. Environmental Variables
- 3.1. LIB_GSL
- 3.2. PATH
4. Installing CythonGSL

I describe how to install GNU Scientific Library (GSL) for CythonGSL in Windows.

CythonGSL is a great module which expose functions of GNU Scientific Library (GSL) to Cython so you can use them in your Cython extension modules conveniently.

In GNU/Linux, you can install GSL library with development header files with a one liner (for example, $ sudo zypper install gsl-devel in openSUSE), but in Windows it is a bit more involved, and if you are not familiar with these kind of stuff (like me) it can take hours to figure out what is wrong. I hope this post will save some time for others.

In sum, you need to do 1) download and unpack GSL with header files and right architecture, 2) set LIB_GSL environmental variable to the GSL directory, and 3) add the path to the bin subdirectory of the GSL directory to PATH environmental variable.

1 Download

1.1 GSL

oscats project has the latest GSL Windows DLL and headers for both 32 and 64-bit. Make sure you download the one for the right architecture (the same one as your Python installation). For example, gsl-1.15-dev-win64.zip for the 64-bit.

1.2 CythonGSL

If you use git, you can download CythonGSL with git clone:

git clone git://github.com/twiecki/CythonGSL.git

or you can just download the zip archive of the master branch.

2 Installing GSL

Just extract the downloaded file to your preferred location such as C:\lib64\GSL or C:\Users\YourName\lib\GSL. In general it is good idea to not have any spaces in the path. From now on I will assume that you have extracted the archive file into C:\lib64\GSL, so if you extract it into different location, change the path accordingly when you follow the instructions below.

3 Environmental Variables

You need to add an environmental variable LIB_GSL and also add the path of \bin subdirectory of your GSL installation to your PATH Environmental variable.

3.1 `LIB_GSL`

Create an environmental variable LIB_GSL with the path to your GSL installation. It is recommended to use Unix style path separator, / instead of \ for this:

LIB_GSL=C:/lib64/GSL

3.2 `PATH`

Add C:\GSL\bin to your PATH environmental variable. This is so Windows can find the two DLL files, libgsl-0.dll and libgslcblas-0.dll. Otherwise, your Cython code will compile, but it will raise the following error at runtime:

ImportError: DLL load failed: The specified module could not be found.

4 Installing CythonGSL

If you have done git clone then just cd CythonGSL and if you have downloaded .zip archive, extract it and go to the directory. Then, following the official instructions,

python setup.py build
python setup.py install

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