Changelog

All notable changes to this project will be documented in this file.

[0.8.0] - Unreleased

n_fermion_sector_view and n_fermion_multisector_view are now parametrized on the type of ranking algorithm used to map basis state indices from a full Hilbert space to a sector. Supported ranking algorithms are combination_ranking (selected by default), staggered_ranking and trie_ranking. All three algorithms are described in M. Wallerberger, K. Held, Phys. Rev. Research 4, 033238 (2022).
Reduced the maximum allowed number of bits in the binary representation of a basis state index (hilbert_space::max_n_bits) to 63. This way hilbert_space::dim() can return a valid value of type sv_index_type even when all 63 bits are used up.
Improved performance and stability of space_partition::merge_subspaces() by switching to a non-recursive variant of the algorithm.
Fixed a negative index bug in n_fermion_sector_view. Credits to Dr. Cezary Śliwa for providing the patch.
Whenever possible, use compiler intrinsics to speed up complex bit manipulation operations (popcount, tzcount, pdep, pext).
Change base type of spin_component to the 1-byte wide std::uint8_t.
New CMake option CPPCHECK_EXTRA_FLAGS. It can be used to pass additional command line flags to cppcheck.

Export namespaced CMake target libcommute::libcommute instead of plain libcommute.
Install CMake configuration files into ${CMAKE_INSTALL_PREFIX}/lib/cmake/libcommute, which is the recommended location.
Upgraded bundled Catch2 to version 2.13.9 (this fixes issue #2 a.k.a. catchorg/Catch2#2178).
Fixed compilation with clang/libc++ 15 (issue #5).
Added project citation information.

New methods space_partition::subspace_basis() and space_partition::subspace_bases().
New methods sparse_state_vector::prune() (two overloads).
New example hubbard_holstein_1d and minor updates to the documentation.

Added an implementation of the StateVector concept for some Eigen 3 types (vectors, vector segments, column-like matrix blocks and one-dimensional Eigen::Map views). The corresponding header file is loperator/state_vector_eigen3.hpp.
New classes n_fermion_sector_view and n_fermion_multisector_view that implement N-fermion (multi)sector views of a state vector. The classes are supplemented with free utility functions make_nf(m)s_view(), make_const_nf(m)s_view(), n_fermion_(multi)sector_size() and n_fermion_(multi)sector_basis_states().
New member typedef hilbert_space::index_types.
New method hilbert_space::has_algebra().
New method space_partition::find_connections().
Renamed the constexpr integer LIBCOMMUTE_MIN_USER_DEFINED_ALGEBRA_ID to min_user_defined_algebra_id so that it does not appear to be a macro.
In the 3-argument constructor of basis_mapper, change the type of the last argument N from int to unsigned int.
Removed methods basis_mapper::make_(const_)view_no_ref(). basis_mapper::make_(const_)view() will now return a non-reference view when supplied with a non lvalue-reference argument.
New CMake option STATIC_ANALYSIS. When enabled, the clang-tidy and cppcheck static analysis tools will be run on the C++ sources of unit tests and examples as part of build process.
Minor bugfixes in unit tests and improvements in coding style.
Reformatted C++ sources using clang-format and a style based on LLVM.