ATLAS stands for Automatically Tuned Linear Algebra Software. ATLAS is both a research project and a software package. This FAQ describes the software package. ATLAS's purpose is to provide portably optimal linear algebra software. The current version provides a complete BLAS API (for both C and Fortran77), and a very small subset of the LAPACK API. For all supported operations, ATLAS achieves performance on par with machine-specific tuned libraries.