## What is LAPACK and BLAS?

BLAS (Basic Linear Algebra Subprograms) is a library of vector, vector-vector, matrix-vector and matrix-matrix operations. LAPACK, a library of dense and banded matrix linear algebra routines such as solving linear systems, the eigenvalue- and singular value decomposition.

## What is Atlas LAPACK?

The ATLAS (Automatically Tuned Linear Algebra Software) project is an ongoing research effort focusing on applying empirical techniques in order to provide portable performance. At present, it provides C and Fortran77 interfaces to a portably efficient BLAS implementation, as well as a few routines from LAPACK.

**How does BLAS work?**

Basic Linear Algebra Subprograms (BLAS) is a specification that prescribes a set of low-level routines for performing common linear algebra operations such as vector addition, scalar multiplication, dot products, linear combinations, and matrix multiplication.

### Does LAPACK need BLAS?

Since LAPACK uses BLAS for the heavy-lifting, just linking to a better-tuned BLAS implementation usually improves the performance sufficiently. As a result, LAPACK is not reimplemented as often as BLAS is.

### What is Libatlas base Dev?

libatlas-base-dev : Automatically Tuned Linear Algebra Software, generic static. libatlas-dev : Automatically Tuned Linear Algebra Software, C header files. libatlas-doc : Automatically Tuned Linear Algebra Software, documentation.

**What is Atlas Linux?**

math-atlas.sourceforge.net. Automatically Tuned Linear Algebra Software (ATLAS) is a software library for linear algebra. It provides a mature open source implementation of BLAS APIs for C and Fortran77. ATLAS is often recommended as a way to automatically generate an optimized BLAS library.

#### Does Eigen use Blas?

Eigen: Using BLAS/LAPACK from Eigen. Since Eigen version 3.3 and later, any F77 compatible BLAS or LAPACK libraries can be used as backends for dense matrix products and dense matrix decompositions. When doing so, a number of Eigen’s algorithms are silently substituted with calls to BLAS or LAPACK routines.

#### Does Blas GPU?

R. With nvblas, nvidia offers a GPU-based BLAS-library, which it claims to be significantly faster than standard procedures. For this comparison we compare R’s default BLAS, the optimized libraries ATLAS and OpenBLAS (all of which are using CPUs only) with nvblas (which uses CPU and GPU).

**Is Eigen header only?**

How to “install” Eigen? In fact, the header files in the Eigen subdirectory are the only files required to compile programs using Eigen. The header files are the same for all platforms. It is not necessary to use CMake or install anything.

## What does Atlas mean?

Automatically Tuned Linear Algebra Software ( ATLAS) is a software library for linear algebra. It provides a mature open source implementation of BLAS APIs for C and Fortran77 . ATLAS is often recommended as a way to automatically generate an optimized BLAS library.

## What is the Atlas project?

The ATLAS (Automatically Tuned Linear Algebra Software) project is an ongoing research effort focusing on applying empirical techniques in order to provide portable performance. At present, it provides C and Fortran77 interfaces to a portably efficient BLASimplementation, as well as a few routines from

**How do I integrate the Atlas Blas with LAPACK?**

When integrating the ATLAS BLAS with LAPACK an important consideration is the choice of blocking factor for LAPACK. If the ATLAS blocking factor is small enough the blocking factor of LAPACK could be set to match that of ATLAS. To take advantage of recursive factorization, ATLAS provides replacement routines for some LAPACK routines.

### Where can I find Atlas documentation?

If you have downloaded the ATLAS source, your ATLAS/doc directory contains some useful documentation, though it is often more dated than the info in the errata and online. If (and only if) neither of these sources provides the information you need, you can can submit a support request to: the ATLAS support tracker.