Grafana Mimir vs n1qn1c

n1qn1c is a quasi-Newton optimization routine translated from Fortran to C, used as a solver backend by the nlmixr2 modeling stack rather than called directly by most users. Its two 2026 releases are a concentrated safety pass: global state converted to thread_local, static removed from local variables in the translated code, integer overflow guards added, and memory leaks closed in the R callback wrappers — plus the gcc-asan and valgrind fixes CRAN asked for.

The package is being hardened for use inside a parallel modeling framework rather than extended. The audit that produced the thread-safety work also surfaced two plain bugs in features users would have assumed worked: restart = TRUE left the mode at 2 instead of 3 because of a typo, and assign = TRUE referenced the wrong field name so the compressed Hessian was never written to the supplied environment. Earlier work points the same direction — the 6.0.1-12 function-pointer interface exists so nlmixr2est does not need resubmission when this package changes.

Expect further memory-safety and sanitizer work rather than algorithmic change; a Fortran-translated numerical core under CRAN's checking regime generates that kind of release indefinitely.