# General aspects

The ropenblas is a package designed to facilitate the linking of the library OpenBLAS with the language R. The package, which works only for Linux systems, will automatically download the latest source code from the OpenBLAS library and compile the code. The package will automatically bind the language R, through the ropenblas() function, to use the OpenBLAS library. Everything will be done automatically regardless of the Linux distribution you are using.

You can also specify older versions of the OpenBLAS library. Automatically, if no version is specified, the ropenblas package will consider the latest version of the library OpenBLAS.

Considering using the OpenBLAS library rather than the BLAS may bring extra optimizations for your code and improved computational performance for your simulations, since OpenBLAS is an optimized implementation of the library BLAS.

Some of the reasons why it is convenient to link R language to the use of BLAS optimized alternatives can be found here. Several other benchmarks that point to improved computing performance by considering the library OpenBLAS can be found on the internet.

The ropenblas package, by rcompiler() function is also useful if you want to install different versions of the R language. The different versions, specified by the user of the R language, will be compiled and will also be linked to the OpenBLAS library. If you want to switch between compiled versions of the R language, no compilation is needed anymore. This allows you to avoid having to get your hands dirty with tedious operating system settings, regardless of your GNU/Linux distribution. Another great use of the rcompiler() function is that you will not be dependent on updating your GNU/Linux distribution repositories and you can always have the latest version of the R language.

The use of the ropenblas package will return warnings that help you proceed with the use of the functions. If your internet is not working or if any dependency on the operating system is not present, the package will let you know.

# Advantages of using ropenblas package

Some advantages of using the ropenblas library:

• Everything is done within the R language;

• The procedure will be the same for any Linux distribution;

• The OpenBLAS library will be compiled and you will choose which build version to bind to R, regardless of your Linux distribution;

• If your GNU/Linux distribution does not have updated versions of OpenBLAS, it matters little. The ropenblas package fetches the latest stable release of the OpenBLAS library development account on GitHub;

• You do not need to know Linux well. In some distributions, it may not be so simple for a less experienced user to compile and link the library to the OpenBLAS library with the R language;

• It is much easier to direct a person to link OpenBLAS with R saying “run ropenblas() within R” than asking that person to verify that an unoptimized version of BLAS installed on the system. Then you have to guide the removal of the unoptimized version of BLAS and guide it to the installation of the library OpenBLAS through the most diverse procedures depending on the GNU/Linux distribution used;

• With the rcompiler() function you can build any version of R into your computer architecture, which includes the most stable version of the language;

• What is the latest stable version of R? Are you too lazy to go to the R site? Run ropenblas::last_version_r(major = NULL).

# Dependencies

You must install the following dependencies on your operating system (Linux):

1 - GNU Make: GNU Make utility to maintain groups of programs;

2 - GNU GCC Compiler (C and Fortran): The GNU Compiler Collection - C and Fortran frontends.

Do not worry that you will be notified if any of these dependencies are not installed.

# Installation

Installing the ropenblas library is easy and will require you to have installed the devtools package. This will allow you to install the ropenblas package directly from GitHub. To install, after installing the devtools package, do:

remotes::install_github(repo = "prdm0/ropenblas", force = TRUE)

or

install.packages("ropenblas")

# Use

The ropenblas package currently provides five functions: ropenblas(), rcompiler(), last_version_openblas(), last_version_r(), link_again() and rnews(). First of all, do:

library(ropenblas)

## ‘ropenblas’ function

Installing, compiling, and linking the OpenBLAS version 0.3.13 library to the R language:

## ‘last_version_r’ function

Given the higher version, the function will return the latest stable version of the R language. See the following example:

## ‘last_version_openblas’ function

The last_version_openblas() function automatically searches OpenBLAS library versions in the official GitHub project.

## ‘rcompiler’ function

This function is responsible for compiling a version of the R language. The x argument is the version of R that you want to compile. For example, x = "4.0.4" will compile and link R-4.0.4 version as the major version on your system. By default (x = NULL) will be compiled the latest stable version of the R.

For example, to compile the latest stable version of the R language, do:

Regardless of your GNU/Linux distribution and what version of R is in your repositories, you can have the latest stable version of the R language compiled into your computer architecture.

You can use the rcompiler() function to compile different versions of R. For example, running rcompiler(x = "3.6.3") and rcompiler() will install versions 3.6.3 and 4.0.0 on its GNU/Linux distribution, respectively. If you are in version 4.0.0 of R and run the code rcompiler(x = "3.6.3") again, the function will identify the existence of version 3.6.3 in the system and give you the option to use the binaries that were built in a previous compilation. This avoids unnecessarys compilations.

## ‘rnews’ function

Returns the contents of the NEWS.html file in the standard browser installed on the operating system. The NEWS.html file contains the main changes from the recently released versions of the R language. The goal is to facilitate the query by invoking it directly from the R command prompt. The rnews function is analogous to the news function of the utils package. However, using the news command in a terminal style bash shell is possible to receive a message like:

> news()
starting httpd help server ... done
Error in browseURL(url) : 'browser' must be a non-empty character string

If pdf = FALSE (default), the NEWS.html file will open in the browser, otherwise NEWS.pdf will be opened. If dev = FALSE (default), it will not show changes made to the language development version. To see changes in the development version, do dev = TRUE.