OpenBLAS is a highly optimized Basic Linear Algebra Subprograms (BLAS) library, serving as a drop-in replacement for GotoBLAS2. It provides accelerated linear algebra routines for scientific computing, machine learning, and high-performance applications across a wide range of architectures.

How It Works

OpenBLAS leverages architecture-specific assembly optimizations for various CPUs, including x86, ARM, POWER, and RISC-V. It dynamically detects the target CPU at runtime or can be configured to optimize for a specific CPU during compilation. This approach ensures maximum performance by utilizing instruction sets like AVX, AVX2, AVX512, and FMA where available.

Quick Start & Requirements

• Installation: Build from source using make or cmake. Binary packages are available for Windows.
• Dependencies: GNU Make or CMake, C compiler (GCC/Clang), optional Fortran compiler. Specific CPU targets may require newer compiler versions.
• Resources: Compilation time varies by target and system.
• Docs: openmathlib.org/OpenBLAS/docs/

Highlighted Details

• Supports a vast array of CPU architectures and instruction sets.
• Dynamic architecture detection (DYNAMIC_ARCH=1) for broad compatibility.
• Optional integration with IBM MASS library for POWER CPUs.
• Includes LAPACK routines.

Maintenance & Community

• Active development with a develop branch.
• Community support via GitHub Discussions and mailing lists.
• Contact: github.com/OpenMathLib/OpenBLAS/discussions
• Issues: github.com/OpenMathLib/OpenBLAS/issues

Licensing & Compatibility

• BSD 3-Clause License. Permissive for commercial use and closed-source linking.

Limitations & Caveats

• Experimental support for macOS/iOS and some BSD variants.
• Building for multiple architectures (e.g., x86_64 and ARM64) in a single library is not supported.
• Compiler version requirements exist for certain CPU optimizations (e.g., AVX512 requires GCC/LLVM 6+).