The BLAS (Basic Linear Algebra Subprograms) are routines
that provide standard building blocks for performing basic vector and matrix
operations. The Level 1 BLAS perform scalar, vector and vector-vector
operations, the Level 2 BLAS perform matrix-vector operations, and the Level 3
BLAS perform matrix-matrix operations. Because the BLAS are efficient,
portable, and widely available, they are commonly used in the development of
high quality linear algebra software, LAPACK for example.