RcppArmadillo 15.0.2-2 on CRAN: Transition to Armadillo 15

Fri, 19 Sep 2025 07:47:00 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) 1261 other packages on CRAN, downloaded 41.4 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 647 times according to Google Scholar.

This versions updates the 15.0.2-1 release from last week. Following fairly extensive email discussions with CRAN, we are now accelerating the transition to Armadillo. When C++14 or newer is used (which after all is the default since R 4.1.0 released May 2021, see WRE Section 1.2.4), or when opted into, the newer Armadillo is selected. If on the other hand either C++11 is still forced, or the legacy version is explicitly selected (which currently one package at CRAN does), then Armadillo 14.6.3 is selected.

Most packages will not see a difference and automatically switch to the newer Armadillo. However, some packages will see one or two types of warning. First, if C++11 is still actively selected via for examples CXX_STD then CRAN will nudge a change to a newer compilation standard (as they have been doing for some time already). Preferably the change should be to simply remove the constraint and let R pick the standard based on its version and compiler availability. These days that gives us C++17 in most cases; see WRE Section 1.2.4 for details. (Some packages may need C++14 or C++17 or C++20 explicitly and can also do so.)

Second, some packages may see a deprecation warning. Up until Armadillo 14.6.3, the package suppressed these and you can still get that effect by opting into that version by setting -DARMA_USE_LEGACY. (However this route will be sunset ‘eventually’ too.) But one really should update the code to the non-deprecated version. In a large number of cases this simply means switching from using arma::is_finite() (typically called on a scalar double) to calling std::isfinite(). But there are some other cases, and we will help as needed. If you maintain a package showing deprecation warnings, and are lost here and cannot workout the conversion to current coding styles, please open an issue at the RcppArmadillo repository (i.e. here) or in your own repository and tag me. I will also reach out to the maintainers of a smaller set of packages with more than one reverse dependency.

A few small changes have been made internal packaging and documentation, a small synchronization with upstream for two commits since the 15.0.2 release, as well as a link to the ldlasb2 repository and its demonstration regarding some ill-stated benchmarks done elsewhere.

The detailed changes since the last CRAN release follow.

Changes in RcppArmadillo version 15.0.2-2 (2025-09-18)

Minor update to skeleton Makevars,Makevars.win

Update README.md to mention ldlasb2 repository

Minor documentation update (#487)

Synchronized with Armadillo upstream (#488)

Refine Armadillo version selection in coordination with CRAN maintainers to support transition towards Armadillo 15.0.*

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.