sci-libs/hypre
Parallel matrix preconditioners library
USE Flags
debug
Global: Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see http://www.gentoo.org/proj/en/qa/backtraces.xml
examples
Global: Install examples, usually source code
fortran
Global: Adds support for fortran (formerly f77)
int64
Global: Install the 64 bits integer library
openmp
Global: Build support for the OpenMP (support parallel computing), requires >=sys-devel/gcc-4.2 built with USE="openmp"
mpi
Global: Adds MPI (Message Passing Interface) layer to the apps that support it