BLAS1 is a library of MATLAB routines which implement the Level 1 BLAS, or Basic Linear Algebra Subprograms.
The BLAS are a small core library of linear algebra utilities, which can be highly optimized for various architectures. Software that relies on the BLAS is thus highly portable, and will typically run very efficiently. The LINPACK and LAPACK linear algebra libraries make extensive use of the BLAS.
The Level 1 BLAS are primarily for use in vector operations. In certain cases, they may also be used to operate on the rows or columns of a two-dimensional array.
It is worth questioning whether one should try to implement the Level 1 BLAS in MATLAB: for one thing, the MATLAB language makes it very easy to carry out vector operations, even with nonunit incrementing on the vector indices. Moreover, MATLAB actually makes it more difficult to stick with the syntax of the BLAS, since it is not so easy to make a two dimensional array "look like" a vector.
In particular, if you want to work on a row of a matrix, MATLAB essentially prefers you to make a temporary vector, as in "A(3,1:N)"; in the standard BLAS, you would instead pass the location of the first entry, A(3,1), and an increment, LDA, that will lead to the next entry of the row. This is not easy or natural to do in MATLAB. Still, for consistency, I have gone ahead and tried to make a reasonable effort at implementing the Level 1 BLAS.
Copies of the BLAS1 library are made available in single or double precision using real or complex arithmetic. For more information, refer to:
BLAS1 is also available in a C++ version and a FORTRAN77 version and a FORTRAN90 version.
BLAS2 is a FORTRAN90 library which handles matrix-vector operations.
BLAS3 is a FORTRAN90 library which handles matrix-matrix operations.
ESSL is the IBM Engineering and Scientific Subroutine Library which includes an implementation of the BLAS1 routines.
GSL is the Gnu Scientific Library which includes an implementation of the BLAS1 routines.
LAPACK is a FORTRAN90 library which is a linear algebra package that uses the BLAS1 routines.
LINPACK is a MATLAB library which is a linear algebra package that uses the BLAS1 routines.
NMS is a FORTRAN90 library which includes BLAS1.
PETSC is a scientific library for use in parallel computation which includes an implementation of the BLAS1 routines.
SLATEC is a FORTRAN90 library which includes BLAS1.
SUPER_BLAS is a C library which is a version of some of the BLAS1 routines.
You can go up one level to the MATLAB source codes.