The Basic Linear Algebra Subroutines are extensively used in LAPACK, in other linear algebra packages, and elsewhere.

There are three levels of BLAS:

- Level 1: Scalar and vector operations
- Level 2: Matrix-vector operations
- Level 3: Matrix-matrix operations

For general information about BLAS see http://www.netlib.org/blas/faq.html.

Optimized versions of the BLAS are available for many computer architectures. See

See also:

- Automatically Tuned Linear Algebra Software (ATLAS)
- BLACS Basic Linear Algebra Communication Subprograms with message passing.
- PSBLAS – Parallel sparse BLAS.

- LAPACK
- LAPACK User’s Guide
- http://en.wikipedia.org/wiki/LAPACK
- ScaLAPACK for parallel distributed memory machines

To install BLAS and LAPACK to work with gfortran, see:

On some linux systems, including the VM for the class, you can install both BLAS and LAPACK via:

```
$ sudo apt-get install liblapack-dev
```

Although iterative methods are often used for sparse systems, there are also excellent software packages for direct methods (such as Gaussian elimination):

*LAPACK examples*for some examples.- Recent list of freely available linear algebra software