The BLAS and LAPACK libraries - Revision history

Emillour at 07:11, 17 October 2023

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Emillour at 11:10, 24 May 2023

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Emillour: Created page with "The BLAS and LAPACK libraries are very common libraries useful for doing linear algebra operations involving matrices and vectors, .e.g. solving linear equation systems, doing..."

2023-05-24T08:08:57Z

Created page with "The BLAS and LAPACK libraries are very common libraries useful for doing linear algebra operations involving matrices and vectors, .e.g. solving linear equation systems, doing..."

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The BLAS and LAPACK 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, edit the '''make.inc''' to fit your settings, if needed and simply run
<syntaxhighlight lang="bash">
make
</syntaxhighlight>
which should produce the static library '''blas_UNIX.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:
<syntaxhighlight lang="bash">
ln -s blas_UNIX.a libblas.a
</syntaxhighlight>

=== Compiling the LAPACK library ===
Assuming you dowloaded the package in a "LAPACK" directory

[[Category:FAQ]]

@@ Line 3: / Line 3: @@
 == Using package managers etc. ==
-In many cases, obtaining and installing the BMAS and LAPACK libraries can be done via the system's package manager; e.g. under Ubuntu-Linux with:
+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.
+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 ==

@@ Line 37: / Line 37: @@
 make
 </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.
+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 ==

@@ Line 33: / Line 33: @@
 cd lapack-3.11.0
 </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 the run:
+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">
 make
 </syntaxhighlight>
 == Linking to the libraries ==
@@ Line 43: / Line 44: @@
 -Lpath/to/the/LAPACK/library -llapack -Lpath/to/the/BLAS/library -lblas
 </pre>
-at compile time. Note the ordering: as some LAPACK routines reliy on BLAS routines one must specify the LAPACK library first
+at compile time. Note the ordering: as some LAPACK routines rely on BLAS routines one must specify the LAPACK library first
 [[Category:FAQ]]

@@ Line 1: / Line 1: @@
-The BLAS and LAPACK 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.
@@ Line 20: / Line 20: @@
 make
 </syntaxhighlight>
-which should produce the static library '''blas_UNIX.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:
+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:
 <syntaxhighlight lang="bash">
 ln -s blas_LINUX.a libblas.a
@@ Line 27: / Line 27: @@
 === Compiling the LAPACK library ===
-Assuming you dowloaded the package in a "LAPACK" directory, edit the '''make.inc''' to fit your settings, if needed and simply run
+Assuming you dowloaded the package in a "LAPACK" directory, e.g.:
 <syntaxhighlight lang="bash">
 make