Categorical Regression Splines R package crs version 0.15-45 CRAN Task View: Optimization (https://CRAN.R-project.org/view=Optimization) Regression splines that handle a mix of continuous and categorical (discrete) data often encountered in applied settings. I would like to gratefully acknowledge support from the Natural Sciences and Engineering Research Council of Canada (NSERC, <https://www.nserc-crsng.gc.ca>), the Social Sciences and Humanities Research Council of Canada (SSHRC, <https://www.sshrc-crsh.gc.ca>), and the Shared Hierarchical Academic Research Computing Network (SHARCNET, <https://www.sharcnet.ca>). We would also like to acknowledge the contributions of the GNU GSL authors. In particular, we adapt the GNU GSL B-spline routine gsl_bspline.c adding automated support for quantile knots (in addition to uniform knots), providing missing functionality for derivatives, and for extending the splines beyond their endpoints. Software Imports: boot, stats, quantreg Suggests: ggplot2, knitr, logspline, MASS, quadprog, rgl, rmarkdown, testthat (>= 3.0.0) Jeffrey S. Racine <racinej@mcmaster.ca> Comprehensive R Archive Network (CRAN) Jeffrey S. Racine [aut, cre], Zhenghua Nie [aut], Brian D. Ripley [ctb] (stepCV.R) GPL (>= 3) 2026-06-26 application/tgz https://CRAN.R-project.org/package=crs doi:10.32614/CRAN.package.crs