Sat, 22 Nov 2025

RcppArmadillo 15.2.2-1 on CRAN: Upstream Update, OpenMP Updates

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) 1286 other packages on CRAN, downloaded 42.6 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 659 times according to Google Scholar.

This versions updates to the 15.2.2 upstream Armadillo release made two days ago. It brings a few changes over the RcppArmadillo 15.2.0 release made only to GitHub (and described in this post), and of course even more changes relative to the last CRAN release described in this earlier post. As described previously, and due to both the upstream transition to C++14 coupled with the CRAN move away from C++11, the package offers a transition by allowing packages to remain with the older, pre-15.0.0 ‘legacy’ Armadillo yet offering the current version as the default. During the transition we did not make any releases to CRAN allowing both the upload cadence to settle back to the desired ‘about six in six months’ that the CRAN Policy asks for, and for packages to adjust to any potential changes. Most affected packages have done so (as can be seen in the GitHub issues #489 and #491) which is good to see. We appreciate all the work done by the respective package maintainers. A number of packages are still under a (now formally expired) deadline at CRAN and may get removed. Our offer to help where we can still stands, so please get in touch if we can be of assistance. As a reminder, the meta-issue #475 regroups all the resources for the transition.

With respect to changes in the package, we once more overhauled the OpenMP detection and setup, following the approach take by package data.table but sticking with an autoconf-based configure. The detailed changes since the last CRAN release follow.

Changes in RcppArmadillo version 15.2.2-1 (2025-11-21)

• Upgraded to Armadillo release 15.2.2 (Medium Roast Deluxe)

  • Improved reproducibility of random number generation when using OpenMP

• Skip a unit test file under macOS as complex algebra seems to fail under newer macOS LAPACK setting

• Further OpenMP detection rework for macOS (Dirk in #497, #499)

• Define ARMA_CRIPPLED_LAPACK on Windows only if 'LEGACY' Armadillo selected

Changes in RcppArmadillo version 15.2.1-0 (2025-10-28) (GitHub Only)

• Upgraded to Armadillo release 15.2.1 (Medium Roast Deluxe)

  • Faster handling of submatrices with one row

• Improve OpenMP detection (Dirk in #495 fixing #493)

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

Courtesy of my CRANberries, there is a diffstat report relative to previous release. 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.

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