Difference between revisions of "The BLAS and LAPACK libraries"
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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. | 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. | 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. | ||
| + | |||
| + | == Using package managers etc. == | ||
| + | In many cases, obtaining and installing the BLAS and LAPACK libraries can be done via the system's package manager; e.g. under Ubuntu-Linux with: | ||
| + | <syntaxhighlight lang="bash"> | ||
| + | sudo apt-get install libblas-dev liblapack-dev | ||
| + | </syntaxhighlight> | ||
| + | If you don't have root-like (sudo) privileges, or your system manager doesn't help, then you can always install the libraries from scratch as detailed below. | ||
== Obtaining the source code of the BLAS and LAPACK libraries == | == Obtaining the source code of the BLAS and LAPACK libraries == | ||
| Line 33: | Line 40: | ||
cd lapack-3.11.0 | cd lapack-3.11.0 | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | 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 | + | 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: |
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
make | make | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| + | 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 == | == Linking to the libraries == | ||
| Line 43: | Line 51: | ||
-Lpath/to/the/LAPACK/library -llapack -Lpath/to/the/BLAS/library -lblas | -Lpath/to/the/LAPACK/library -llapack -Lpath/to/the/BLAS/library -lblas | ||
</pre> | </pre> | ||
| − | at compile time. Note the ordering: as some LAPACK routines | + | at compile time. Note the ordering: as some LAPACK routines rely on BLAS routines one must specify the LAPACK library first |
[[Category:FAQ]] | [[Category:FAQ]] | ||
Latest revision as of 08:11, 17 October 2023
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.
Contents
Using package managers etc.
In many cases, obtaining and installing the BLAS and LAPACK libraries can be done via the system's package manager; e.g. under Ubuntu-Linux with:
sudo apt-get install libblas-dev liblapack-dev
If you don't have root-like (sudo) privileges, or your system manager doesn't help, then you can always install the libraries from scratch as detailed below.
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
