Graham, Martin,
So I logged back onto the s390x box we can access. Matrix 1.13-2 does fail the factorization test when doing _R_CHECK_FORCE_SUGGESTS_=false R CMD check --no-manual \ --no-vignettes Matrix_1.3-2.tar.gz and Matrix 1.2-18 passes it. So Graham was right all-along that there was something in the 1.3-0 transition. Now, is that ultimately Matrix or the underlying QR code it uses? I don't know. But it reasonably easy for me to get access (and install the required packages) so once Martin has time to think through an approach or two I can likely test it. Best, Dirk -- https://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org