GeoModels OpenMP source installation
=====================================

GeoModels always remains installable with a serial fallback. OpenMP is active
only when R's source-compilation configuration supplies a non-empty
SHLIB_OPENMP_CFLAGS and the compiler consequently defines _OPENMP.

Before installation, check:

    R CMD config SHLIB_OPENMP_CFLAGS

During R CMD INSTALL, verify that the C compilation and final link commands
contain an OpenMP flag (commonly -fopenmp, or a platform-specific equivalent).
After installation, run:

    library(GeoModels)
    GeoOMP()

The field `compiled` must be TRUE for native OpenMP acceleration. If it is
FALSE, installation was successful and GeoModels is using its serial fallback.

On macOS, Apple clang has no native OpenMP support. To compile the OpenMP path
from source, configure an OpenMP-capable compiler and SHLIB_OPENMP_CFLAGS in a
user or site Makevars file (for example ~/.R/Makevars). The package Makevars
intentionally contains no Homebrew-specific paths or compiler flags, because
such paths are not portable and are rejected by CRAN checks.

The native parallel path supports the Gaussian Matern pairwise marginal and
conditional likelihood for any positive smoothness. Exact half-integers use
closed-form kernels; general smoothness uses a package-local allocation-free
Bessel-K recurrence, so worker threads do not call Rmath warning/error or
allocation paths. Native registration and the serial installation fallback
remain unchanged.
