The BLAS and LAPACK libraries

The BLAS (Basic Linaer Algebra) and LAPACK (Linear Algebra PACKage) libraries are very common libraries useful for doing linear algebra operations involving matrices and vectors, .e.g. solving linear equation systems, doing SVD factorization, etc. In many case they are already installed and available Linux systems, but not always... and then you will have to download and install them yourself.

Obtaining the source code of the BLAS and LAPACK libraries

The Fortran source codes are available on Netlib.org : http://www.netlib.org/blas/ and http://www.netlib.org/lapack/

Compiling the libraries

Prerequisites

All you need are a Fortran compiler and the gmake utility

Compiling the BLAS library

Assuming you dowloaded the package in a "BLAS" directory, e.g.:

wget http://www.netlib.org/blas/blas-3.11.0.tgz
tar xvzf blas-3.11.0.tgz
cd BLAS-3.11.0/

Edit the make.inc to fit your settings (e.g. compiler name and options), if needed and the simply run

make

which should produce the static library blas_LINUX.a. It is good practice to usually use a different naming convention and call the library libblas.a so you can make a symbolic link to have both available:

ln -s blas_LINUX.a libblas.a

Compiling the LAPACK library

Assuming you dowloaded the package in a "LAPACK" directory, e.g.:

wget https://github.com/Reference-LAPACK/lapack/archive/refs/tags/v3.11.0.tar.gz
tar xvzf v3.11.0.tar.gz
cd lapack-3.11.0

copy the provided make.inc.example as make.inc and adapt it to fit your settings (e.g. compiler name and options), if needed, and then run:

make

which should produce the static library liblapack.a. Note that recent versions of LAPACK actually incorporate the BLAS library but with a different name: librefblas.a.

Linking to the libraries

One simply needs to specify options

-Lpath/to/the/LAPACK/library -llapack -Lpath/to/the/BLAS/library -lblas

at compile time. Note the ordering: as some LAPACK routines rely on BLAS routines one must specify the LAPACK library first