Circumventing The Linker: Using SciPy's BLAS and LAPACK Within Cython

BLAS, LAPACK, and other libraries like them have formed the underpinnings of much of the scientific stack in Python. Until now, the standard practice in many packages for using BLAS and LAPACK has been to link each Python extension directly against the libraries needed. Each module that calls these low-level libraries directly has had to link against them independently. The task of finding and linking properly against the correct libraries has, in the past, been a substantial obstacle in the development and distribution of Python extension modules.

Cython has existing machinery that allows C-level declarations to be shared between Cython-compiled extension modules without linking against the original libraries. The Cython BLAS and LAPACK API in SciPy uses this functionality to make it so that the same BLAS and LAPACK libraries that were used to compile SciPy can be used in Python extension modules via Cython. This paper will demonstrate how to create and use these APIs for both Fortran and C libraries in a platform-independent manner.