OpenBLAS

We build OpenBLAS on Travis-CI (for linux aarch64, ppc64, s390x) and github actions for linux, windows, macOS x86_64 and macOS arm64.

First, tarballs are built using do_build_lib in tools/build_steps.sh (on posix in a docker and drectly on macos) or build_openblas.sh on windows.

Then the shared object and header files from the tarball are used to build the wheel via tools/build_wheel.sh, and the wheels uploaded to https://anaconda.org/scientific=python-nightly-wheels/scipy_openblas32 and https://anaconda.org/scientific=python-nightly-wheels/scipy_openblas64 via tools/upload_to_anaconda_staging.sh. For a release, the wheels are uploaded to PyPI by downloading them via tools/dowlnload-wheels.py and uploading via twine.

The wheel is self-contained, it includes all needed gfortran support libraries. On windows, this is a single DLL.

The wheel supplies interfaces for building and using OpenBLAS in a python project like SciPy or NumPy:

Buildtime

• get_include_dir(), get_lib_dir() and get_library() for use in compiler or project arguments
• get_pkg_config() will return a multi-line text that can be saved into a file and used with pkg-config for build systems like meson. This works around the problem of relocatable pkg-config files since the windows build uses pkgconfiglite v0.28 which does not support --define-prefix.

Runtime

• importing will load openblas into the executable and provide the openblas symbols.