openblas

openSUSE specific packaging
===========================

OpenBLAS provides optimized implementations of BLAS and LAPACK.
openSUSE provides three variants:
 * Serial library (libopenblas_serial0)
 * With OpenMP support (libopenblas_openmp0)
 * With threading support (libopenblas_pthreads0)

By default openSUSE uses pthreads version on x86 systems and OpenMP
for other architectures. On x86 systems OpenBLAS uses dynamic
architectures support, so it contains all CPU-related optimizations.

Library Installation Locations
===============================

Starting with version 0.3.31, OpenBLAS libraries are installed in
flavor-specific directories to allow parallel installation:

 * /usr/lib64/openblas-serial/    (serial flavor)
 * /usr/lib64/openblas-openmp/    (OpenMP flavor)
 * /usr/lib64/openblas-pthreads/  (pthreads flavor)

Each directory contains:
 * libopenblas.so.0 - The actual library
 * pkgconfig/openblas.pc - pkg-config file pointing to this flavor
 * cmake/openblas/ - CMake configuration files for this flavor

The system-wide /usr/lib64/pkgconfig/openblas.pc and
/usr/lib64/cmake/openblas links point directly to the flavor-specific
files, ensuring consistent library usage.

Update-Alternatives Support (Compatibility)
============================================

For backward compatibility, compatlib packages are available:
 * compatlibopenblas_serial0
 * compatlibopenblas_openmp0
 * compatlibopenblas_pthreads0

These packages use update-alternatives to provide the traditional
/usr/lib64/libblas.so.3 and /usr/lib64/liblapack.so.3 symlinks.

When upgrading from OpenBLAS 0.3.30 or newer, the compatlib packages
are automatically installed to maintain compatibility with existing
setups. For new installations, they are optional.

How to switch between the various BLAS/LAPACK implementations
=============================================================

If you have a compatlib package installed, you can switch implementations:

BLAS:
 sudo /usr/sbin/update-alternatives --config libblas.so.3

LAPACK:
 sudo /usr/sbin/update-alternatives --config liblapack.so.3

OpenBLAS default flavor:
 sudo /usr/sbin/update-alternatives --config openblas-default

Note: The compatlib packages are incompatible with transactional
enabled OS installations.

More information is available at:

 https://en.opensuse.org/openSUSE:Science_Linear_algebra_libraries