RcppArmadillo 15.2.0-0 on GitHub: New Upstream, Simpler OpenMP

Mon, 20 Oct 2025 16:13:00 CDT

Armadillo is a powerful and expressive C++ template library for linear algebra and scientific computing. It aims towards a good balance between speed and ease of use, has a syntax deliberately close to Matlab, and is useful for algorithm development directly in C++, or quick conversion of research code into production environments. RcppArmadillo integrates this library with the R environment and language–and is widely used by (currently) 1270 other packages on CRAN, downloaded 42 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 650 times according to Google Scholar.

This versions updates to the 15.2.0 upstream release made today. It brings a few changes over Armadillo 15.0 (see below for more). It follows the most recent RcppArmadillo 15.0.2-2 release and the Armadillo 15 upstream transition with its dual focus on moving on from C++11 and deprecation of a number of API access points. As we had a few releases last month to manage the transition, we will sit this upgrade out and not upload to CRAN in order to normalize our update cadence towards the desired ‘about six in six months’ (that the CRAN Policy asks for). One can of course install as usual directly from the GitHub repository as well as from r-universe which also offers binaries for all CRAN platforms.

The transition to Armadillo 15 appears to be going slowly but steadily. We had well over 300 packages with either a need to relax the C++11 setting and/or update away from now-deprecated API access points. That number has been cut in half thanks to a lot of work from a lot of package maintainers—which is really appreciated! Of course, a lot remains to be done. Issues #489 and #491 contain the over sixty PRs and patches I prepared for all packages with at least one reverse dependency. Most (but not all) have aided in CRAN updates, some packages are still outstanding in terms of updates. As before meta-issue #475 regroups all the resources for the transition. If you, dear reader, have a package that is affected and I could be of assistance please do reach out.

The other change we made is to greatly simplify the detection and setup of OpenMP. As before, we rely on configure to attempt compilation of a minimal OpenMP-using program in order to pass the ‘success or failure’ onto Armadillo as a ‘can-or-cannot’ use OpenMP. In the year 2025 one of the leading consumer brands still cannot ship an OS where this works out of the box, so we try to aide there. For all others systems, R actually covers this pretty well and has a reliable configuration variable that we rely upon. Just as we recommend for downstream users of the package. This setup should be robust, but is a change so by all means if you knowingly rely on OpenMP please test and report back.

The detailed changes since the last CRAN release follow.

Changes in RcppArmadillo version 15.2.0-0 (2025-10-20) (GitHub Only)

Upgraded to Armadillo release 15.2.0 (Medium Roast Deluxe)

Added rande() for generating matrices with elements from exponential distributions

shift() has been deprecated in favour of circshift(), for consistency with Matlab/Octave

Reworked detection of aliasing, leading to more efficient compiled code

OpenMP detection in configure has been simplified

More detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the Rcpp R-Forge page.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.