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The libhifir Library

libhifir is a derived work of HIFIR. It is a runtime library with C and Fortran interfaces, and it is provided for convenience for linking with C/Fortran codes.

Installation

After obtaining the C++ interface, one can build and install the C library libhifir. First, navigate to the subfolder libhifir

cd libhifir

Then, compile and install the package using the following commands:

make -j
make PREFIX=/path/to/destination install

For a quick check, you may also want to run make test before make install or make PREFIX=/path/to/destination test after install.

The -j options allows building both 32-bit-integer and 64-bit-integer versions at the same time. By default, PREFIX=/usr/local. In addition, set the LAPACK_LIBS variable if you have customized installation of LAPACK, such as

make LAPACK_LIBS="-L/path/to/openblas/lib -lopenblas" -j

which is also preferable to set LDFLAGS=-Wl,-rpath,/path/to/openblas/lib. Note that LAPACK_LIBS="-llapack -lblas" by default. Note that HIFIR uses OpenMP for computing the Schur complement. You can disable OpenMP by setting USE_OPENMP=0, i.e., make USE_OPENMP=0 -j.

Note that to install to a system directory, you may need to add sudo in front of the make install command.

Once the installation is complete, we will have

  • ${PREFIX}/include/libhifir.h: This is the header file.
  • ${PREFIX}/lib/libhifir_i32.{so,a}: These are shared and static libraries for 32-bit integer builds.
  • ${PREFIX}/lib/libhifir_i64.{so,a}: These are shared and static libraries for 64-bit integer builds.

To use 64-bit library, set -DLIBHIFIR_INT_SIZE=64 while compiling your program, such as

cc -DLIBHIFIR_INT_SIZE=64 my_prog.c -lhifir_i64

Note that by default, libhifir uses 64-bit integer for ind_start array in HIF and sparse matrices for both 32-bit and 64-bit integer builds. In other words, 32-bit and 64-bit integer builds only affect the index array in sparse matrices and HIF preconditioners. To use 32-bit ind_start array, one needs to build libhifir and compile his/her programs with macro -DLIBHIF_INDPTR_SIZE=32.

Examples

libhifir/tests contains some simple testing programs, which illustrate how to call multilevel triangular solve and matrix-vector multiplication in libhifir with both real and complex arithmetics. For comprehensive examples, please refer to the C++ demos under the ../examples directory and adapt them to C by referring to HIFIR's documentation.