Condensed release information

Table of Contents

• Version 3.13.0 (Jan 2026)
• Version 3.12.0 (Nov 2025)
• Version 3.11.0 (Nov 2025)
• Version 3.10.0 (Oct 2025)
• Version 3.9.3 (Oct 2025)
• Version 3.9.2 (Sep 2025)
• Version 3.9.1 (Aug 2025)
• Version 3.9.0 (Jul 2025)
• Version 3.8.0 (Jul 2025)
• Version 3.7.1 (May 2025)
• Version 3.7.0 (Apr 2025)
• Version 3.6.2 (Mar 2025)
• Version 3.6.1 (Mar 2025)
• Version 3.6.0 (Feb 2025)
• Version 3.5.2 (Dec 2024)
• Version 3.5.1 (Dec 2024)
• Version 3.5.0 (Nov 2024)
• Version 3.4.0 (Sep 2024)
• Version 3.3.0 (Jul 2024)
• Version 3.2.0 (Jun 2024)
• Version 3.1.1 (Jan 2024)
• Version 3.1.0 (Jan 2024)
• Version 3.0.3 (Oct 2023)
• Version 3.0.2 (Aug 2023)
• Version 3.0.1 (Jun 2023)
• Version 3.0.0 (Mar 2023)
• Version 2.6.2 (Dec 2022)
• Version 2.6.1 (Sep 2022)
• Version 2.6.0 (Aug 2022)
• Version 2.5.2 (Jun 2022)
• Version 2.5.1 (Jun 2022)
• Version 2.5.0 (May 2022)
• Version 2.4.3 (May 2022)
• Version 2.4.2 (Dec 2021)
• Version 2.4.1 (Dec 2021)
• Version 2.4.0 (Nov 2021)
• Version 2.3.2 (Sep 2021)
• Version 2.3.1 (Sep 2021)
• Version 2.3.0 (Aug 2021)
• Version 2.2.0 (May 2021)
• Version 2.1.2 (Apr 2021)
• Version 2.1.1 (Mar 2021)
• Version 2.1.0 (Feb 2021)
• Version 2.0.1 (Jan 2021)
• Version 2.0.0 (Jan 2021)
• Version 1.5.5 (Aug 2020)
• Version 1.5.4 (Dec 2019)
• Version 1.5.3 (Nov 2019)
• Version 1.5.2 (Jul 2019)
• Version 1.5.1 (Jun 2019)
• Version 1.5.0 (Feb 2019)
• Version 1.4.0 (22 Oct 2018)
• Version 1.3.2 (21 Aug 2018)
• Version 1.3.1 (6 Aug 2018)
• Version 1.3.0 (25 Sep 2017)
• Version 1.2.0 (30 Nov 2015)
• Version 1.1.0 (28 Oct 2015)
• Version 1.0.5 (22 Jul 2015)
• Version 1.0.4 (9 Jun 2015)
• Version 1.0.3 (5 Feb 2015)
• Version 1.0.2 (30 Oct 2014)
• Version 1.0.1 (3 Sep 2014)
• Version 1.0.0 (22 Jul 2014)

Version 3.13.0 (Jan 2026)

• fix bug with missing header file when including yac_config.h after installing YAC with make install (merge request 461)
• fix bug when building Python core bindings with –disable-utils (merge request 458)
• replaces --with-global-id-type with precious environment variable YAC_INT

Version 3.12.0 (Nov 2025)

• adds configure option --with-global-id-type to select the type used for global index values. Supported types are int (default), long, and long long. This enables handling datasets with more than 2^31 elements. (merge request 449)

Version 3.11.0 (Nov 2025)

• adds support for collection selections (merge request 420), which can be can be configured via:
  • YAML configuration file
  • user interface:
    • associated C interfaces:
      yac_cset_ext_couple_config_collection_selection
      yac_cget_ext_couple_config_collection_selection
    • associated Fortran interfaces:
      yac_fdef_couple
    • associated Python interfaces:
      yac::YAC::def_couple
• adds new interface yac_cset_global_index_yac_int, which enables setting global indices larger than INT_MAX (when yac_int is defined as long, for example) (merge request 447)
• adds logging capabilities to the yac.core module. (merge request 448)

Version 3.10.0 (Oct 2025)

• adds python bindings for the core API
• adds YAC Python Weight File Generator

Version 3.9.3 (Oct 2025)

• added instructions for building YAC on Windows WSL (merge request 429)
• added python/requirements.txt for easier Python environment setup (merge request 427)
• added macro YAC_VERSION_GREATER_EQUAL for easier API compatibility checks at compile time (see merge request 408)
  • C: automatically included via #include "yac.h"
  • Fortran: need to explicitly #include "yac_version_check.h"
• added support for NaN as a fixed value for Fixed value interpolation (see merge request 415)
• improved error handling when installing Python bindings (see merge request 411)
• fixes bug in yac_ctest (see merge request 426)
• fixes serval bugs in get_async operation in the basic interpolation operators (see merge request 433)

Version 3.9.2 (Sep 2025)

• improved angle computation. Many thanks to Hongyu Chen (UC Davis) for pointing out this formula
• fix: use duplicated MPI_Comm in interpolation
• improve documentation
• make YAC without MCI independent from libfyaml (see issue 203)

Version 3.9.1 (Aug 2025)

• fixes bug that prevented extended configurations for Source to Target mapping from being properly applied
• improves performance of Source to Target mapping for large spread distances

Version 3.9.0 (Jul 2025)

• adds user interface for retrieving MPI handshake group name used by internally YAC for the initial splitting of MPI_COMM_WORLD (see yac_cget_mpi_handshake_group_name, yac_fget_mpi_handshake_group_name, yac::mpi_handshake_group_name)
• improves documentation on how to build YAC on an Ubuntu system
• adds extended configurations for Source to Target mapping
  • associated C interfaces:
    yac_cadd_interp_stack_config_spmap_ext
    yac_cget_ext_spmap_config
    yac_cfree_ext_spmap_config
    yac_cset_ext_spmap_config_spread_distance
    yac_cset_ext_spmap_config_max_search_distance
    yac_cset_ext_spmap_config_weight_type
    yac_cset_ext_spmap_config_scale_type
    yac_cset_ext_spmap_config_src_cell_area_config_yac
    yac_cset_ext_spmap_config_tgt_cell_area_config_yac
    yac_cset_ext_spmap_config_src_cell_area_config_file
    yac_cset_ext_spmap_config_tgt_cell_area_config_file
    yac_cget_spmap_overwrite_config
    yac_cfree_spmap_overwrite_config
    yac_cset_spmap_overwrite_config_src_point_selection_bnd_circle
    yac_cset_spmap_overwrite_config_spread_distance
    yac_cset_spmap_overwrite_config_max_search_distance
    yac_cset_spmap_overwrite_config_weight_type
  • associated Fortran interfaces:
    yac_fadd_interp_stack_config_spmap
    yac_fget_spmap_overwrite_config_bnd_circle
    yac_ffree_spmap_overwrite_config
    
• fixes bug in Python interface that led to crashes when calling help(...) or auto-completion under certain circumstances.
  (see issue 195)

Version 3.8.0 (Jul 2025)

• introduces a Style Guide for the YAC documentation
• adds default values to interpolation definition Python interfaces
• improvement of yac_replay.py and addition of yac_record.py (see Recording and Replaying Coupling Data)
• adds new interface for querying about local definition status of a field (see yac_cget_field_is_defined, yac::yac_fget_field_is_defined, yac::YAC::get_field_is_defined)
• adds additional reader for ICON grid files that also includes grid mask and cell centers (see yac_read_icon_basic_grid_parallel_2)
• adds new interface that returns the MPI communicator of a given YAC instance
• in case different components share a grid (same grid name), intermediate results during the weight computation are now being shared
  • can significantly improve performance during End of Definition Phase
• adds new reader for EXODUS-formated NetCDF grid files (see yac_read_exodus_basic_grid_parallel)
• adds YAC Weight File Generation Tool

Version 3.7.1 (May 2025)

• improved doxgen documentation
  • adds usage examples
  • unit tests are now listed under Test list
• performance improvements
  • better load balancing during End of Definition Phase
  • replaces yaxt-xmap with internal version that provided more stable performance
  • changes algorithm in sphere part algorithm
    • can now utilize OpenMP
    • better performance on vector processors
• adds testing of and fixes to examples
• multiple minor bug fixes

Version 3.7.0 (Apr 2025)

• adds configuration option the specifies what YAC is supposed to do in case it was tasked to generate a weight file, but a file with the same name already exists (see YAML configuration option and yac_cset_ext_couple_config_weight_file_on_existing / yac_cget_ext_couple_config_weight_file_on_existing)
• adds new options to Interpolation from weight file (see YAML configuration options and yac_cadd_interp_stack_config_user_file_2)
  • on_missing_file specifies what the interpolation method is supposed to do in the case respective weight file does not exist
  • on_success specifies whether the interpolation stack is supposed to be continued after a weight file was succuessfully read
• partial rework of generation of YAC-internal domain decomposition
  • improved load balance
  • adds usage of OpenMP
  • improved performance on NEC vector maschines

Version 3.6.2 (Mar 2025)

• adds reader for SCRIP-formated grid files that only contain cell centers and no corner information to YAC utilities (yac_read_scrip_cloud_basic_grid_parallel, yac_read_scrip_cloud_basic_grid, yac_read_scrip_grid_information, yac_read_scrip_generic_basic_grid_parallel)

Version 3.6.1 (Mar 2025)

• various fixes
• adds new interface for adding a RBF interpolation to an interpolation stack (yac_cadd_interp_stack_config_rbf, yac::yac_fadd_interp_stack_config_rbf, yac::InterpolationStack::add_rbf)
• improved computation of barycentric coordinates for regular grids whose cell edges follow circles of constant longitude/latitude
• adds new interface for defining an regular grid with rotated poles (yac_cdef_grid_reg2d_rot, yac::yac_fdef_grid::yac_fdef_grid_reg2d_rot_real, yac::yac_fdef_grid::yac_fdef_grid_reg2d_rot_dble, yac::Reg2dGrid (with north_pole argument))
• adds new interface for defining an points on a regular grid with rotated poles (yac_cdef_points_reg2d_rot, yac::yac_fdef_points::yac_fdef_points_reg2d_rot_real, yac::yac_fdef_points::yac_fdef_points_reg2d_rot_dble)
• adds configure option to disbale Fortran interface (--disable-fortran-bindings)

Version 3.6.0 (Feb 2025)

• adds new feature: Raw data exchange
• new improved design and layout o documentation
• improves performance of End of Definition Phase
  • removes unneccessary computations
  • makes use of OpenMP
  • adds specialised optimisation for vector machines (compile with -DYAC_NEC_EXPERIMENTAL to enable this)

Version 3.5.2 (Dec 2024)

• fixes installation of Python bindings
• fixes memory leaks (some statically held memory was not freed)
• improves handling for NaN's in case they are use fallback values in Dynamic fractional masking
• minor fix in area computation
• adds workaround for issue in test suite with Intel icx compiler

Version 3.5.1 (Dec 2024)

• improves compatibility with older Python versions
• make yaxt exchanger being used in put/get operations configurable (see Configuration of yaxt exchanger method)

Version 3.5.0 (Nov 2024)

• various fixes
• adds source/target field to configuration file for making grid and component definition more flexible
• adds new interface for querying the source field information of a target field (yac_cget_field_source, yac::yac_fget_field_source, yac::YAC::get_field_source)
• adds new interface for defining an unstructed grid with explicit definition of the edges (yac_cdef_grid_unstruct_edge, yac::yac_fdef_grid::yac_fdef_grid_nonuniform_edge_dble, yac::yac_fdef_grid::yac_fdef_grid_unstruct_edge_dble, yac::UnstructuredGridEdge)
• adds feature to Source to Target mapping that enables reading of cell areas from file for scaling
• improves documentation
  • adds information on YAC components (YAC libraries and YAC tools)
  • updates documentation on Configuration, Building and Installation for Different Systems
  • restructures Main page, "Related pages"
• adds abort handler routine interfaces to yac_core.h

Version 3.4.0 (Sep 2024)

• various fixes
• the coupling configuration file now accepts array of grid names for each coupling
• rework of internal implemention of NNN search
• adds support for grids containing only vertices and no cells (yac_cdef_grid_cloud and yac::CloudGrid)
• vtk file generated by tool weights2vtk now also contains source and target ids for all links
• the NNN zero weighting option now produces links that all use the same source cell (should be much faster)
• adds new interface for querying the calendar (yac_cget_calendar)
• various improvements for plot_weights.py, including:
  • fix for the extent calculation
  • configurable projection
  • add stencil-only flag to plot only cells that are involved at the highlighted stencil
  • improve visualization
• adds feature that allows the user to define whether YAC aborts or not in case a coupling was defined, but at least one of the two associated fields was not defined (see missing_definition_is_fatal configuration file flag)
• adds new interface for computing cell areas (yac_basic_grid_compute_cell_areas, yac_ccompute_grid_cell_areas, yac_fcompute_grid_cell_areas, and yac::Grid::compute_grid_cell_areas)
• adds debug options which writes out all user-provided definitions (components, grid, field)
  • configurable via configuration file (yaml_include_definitions)
  • new "include_definitions"-argument for interfaces yac_cset_config_output_file, yac_cset_config_output_file_instance, yac::yac_fset_config_output_file, and yac::YAC::set_config_output_file
• debuggging tool weights2vtk now supports weight file generated by the CDOs
• adds new debugging tool debug_grid2vtk that can convert a debug grid NetCDF file written by YAC to a vkt file, which is easiert to visualize using for example Paraview

Version 3.3.0 (Jul 2024)

• various fixes
• adds new max_search_distance-Option to N-Nearest-Neighbour interpolation
• reworks writing out of configurations files
  • removes yac_cdisable_config_output/yac_cdisable_config_output_instance
  • removes yac_cenable_config_output_yaml/yac_cenable_config_output_yaml_instance
  • adds yac_cset_config_output_file / yac_cset_config_output_file_instance
  • changes how this feature is set up in YAML configuration file
• removes source/target grid name from interfaces for setting up Interpolation from weight file
• adds functionality that generates an interpolation stack from string
• adds functionality that writes grid data provided in Grid Definition to file, which can be configured via:
  • YAML configuration file
  • user interface: Writing of Grid Data to File
• YAC utility ICON grid file reader can now handle arbitrary number of vertices per cell
• adds YAC utility function for writing a cubed sphere grid to file (can be read in using ICON grid file reader)
  • yac_write_cubed_sphere_grid
• Improve plot_weights.py script for weight visualisation
  • add documentation
  • add a legend
  • interactive label visibility
  • fixes for the extent computation for label visualisation

Version 3.2.0 (Jun 2024)

• various fixes
• significant reduction in compiler warnings
• additional consistency checks for data provided by the user
• improved test coverage
• restructuring of files, directories, and Fortran modules
  • renames yac_interface.h to yac.h (yac_interface.h is kept until next major release of YAC)
  • renames yac_finterface.F90 to yac_global.F90
  • renames mo_yac_finterface.F90 to yac_module.F90
  • renames Fortran module mo_yac_finterface to yac (mo_yac_finterface is kept until next major release of YAC)
  • renames Fortran module mo_yac_core to yac_core (mo_yac_core is kept until next major release of YAC)
  • renames Fortran module mo_yac_utils to yac_utils (mo_yac_utils is kept until next major release of YAC)
  • renames directory contrib to src/utils
  • renames directory python/tests to tests/python
  • libyac.a is now deprecated and split into libyac_core.a, libyac_mci.a, and libyac_utils.a
• restructuring of configuration
  • restores option --disable-netcdf
  • adds option --enable-deprecated (allows usage of old names)
  • adds option --enable-openmp (enables usage of OpenMP by YAC)
  • replaces --enable-lib-core-only with --disable-mci (--enable-lib-core-only is kept until next major release of YAC)
  • adds option --enable-utils
  • adds pkg-configs for core, utils, and mci
• extends workaround for NVHPC compiler to version 24 and older
• some renaming of C-interfaces
  • yac_get_grid_size -> yac_cget_grid_size
  • yac_get_points_size -> yac_cget_points_size
• adds Fortran interfaces
  • yac::yac_fget_grid_size
  • yac::yac_fget_points_size
  • yac::yac_fget_default_instance_id
  • yac::yac_fdef_comp_dummy
• adds Python interfaces and properties
  • yac::YAC::from_id
  • yac::YAC::cleanup
  • yac::Field::update
  • yac::Field::action
  • yac::Component::size
  • yac::Component::rank
  • yac::Reg2dGrid::def_points_unstruct
  • yac::Curve2dGrid::def_points_unstruct
• adds logging to Python interface
• adds a Python script (yac_replay.py) that is freely configurable and provides field data from an input file through YAC to other components
• adds usage of OpenMP to performance critical kernels in YAC
• adds support for scaling with user defined sphere radius to Source to Target mapping
• adds macros YAC_VERSION_MAJOR, YAC_VERSION_MINOR, YAC_VERSION_PATCH, and YAC_VERSION_TWEAK
• adds debug option which writing of the global coupling configuration to file after End of Definition Phase (see YAML configuration file)
• adds support for negative lags

Version 3.1.1 (Jan 2024)

• adds workaround for performance issue of the OpenMPI implementation of routine MPI_Group_difference
• adds support for asynchronous get operations
  • adds new routines yac_cget_async and yac_cwait
  • yac_ctest now supports checking for completion of asynchronous get operations
  • adds Python Coroutines for put and get operations

Version 3.1.0 (Jan 2024)

• various fixes
• rework of directory structure
  • code from src and tests directory is now moved to new subdirectories:
    • core (all code required for execution of weight computation and basic exchanges)
    • mci (model coupling interface; all code related to the user interface)
  • new tools directory
• change to configure
  • new option --enable-lib-core-only
    • builds core functionality into libyac_core
    • removes the dependency on libfyaml, since mci is not built
  • new option --with-pic
  • --enable-lib-only replaced by --disable-examples and --disable-tools
  • removed --enable-netcdf
• more consistent naming in YAC
  • all exposed routines and objects have a yac_ prefix
  • functionality from libgridio is now in libyac_utils
• adds functionality that allows the duplication of stencils stored in struct yac_interp_weights for other target points (yac_duplicate_stencils)
• adds Fortran interface for core functionality (mo_yac_core)
• adds Fortran interface for utility functionality (mo_yac_utils)
• additional functionality for SCRIP grid file reader (see yac_read_scrip_basic_grid)
  • support for lon/lat edges
  • detection of duplicated cells
  • parallel reading (yac_read_scrip_basic_grid_parallel)
• additional functionality for writing weight files
  • optional global grid sizes in weight files (see yac_interp_weights_write_to_file)
  • 64-bit offset weight files
• removes redirstdout functionality
• new weighting option for N-Nearest-Neighbour interpolation (YAC_INTERP_NNN_ZERO)
• new interpolation method Nearest Corner Cells interpolation
• improved 2nd order conservative weight computation at mask and grid edges
• new examples
  • access_core
    • demonstrates access of core functionality from fortran
  • toy_output
    • basic output server
• YAC is now REUSE-compliant

Version 3.0.3 (Oct 2023)

• various fixes
• adds support for custom error handler
  • yac_set_abort_handler
  • yac_restore_default_abort_handler
  • yac_get_abort_handler
  • yac_get_default_abort_handler
• improve plot_weights.py
  • support for SCRIP formated grid files
• makes ranks doing I/O configurable (see Configuration of parallel IO in YAC)
• add support for reading yaml configuration in Python

Version 3.0.2 (Aug 2023)

• various fixes
• new interfaces for
  • getting default instance id (yac_cget_default_instance_id)
  • defining a component before the collective Component Definition (yac_cpredef_comp)
  • for checking status of an asynchronous exchange operation (yac_ctest)
• adds support for Dynamic fractional masking (includes various new interfaces)
• improved code structure in interpolation.c
• adds plausibility check for vertex coordinates provided by the user
• replaces usage of MPF in crossproduct computation with kahan summation (required for CPUs that do not support long double with more than 64 bit)
• Extends options for the Definition of Couples
  • Fortran/Python:
    • additional optional arguments
  • C:
    • routines for the definition of an extended coupling configuration
    • new yac_cdef_couple_custom interface that has an additional argument for the extended coupling configuration
• adds support for scaling fractors and summand (can be used for unit conversions in the interpolation)
  • can be configured either through the YAML configuration file the user interface
• adds support for scrip-formated grid files to tool weights2vtk
• adds support for named masks
• adds various workarounds for current NVHPC compiler
• adds Python tool weight visualisation

Version 3.0.1 (Jun 2023)

• various fixes
• reduces compiler warnings
• adds new interface for unstructured grids with edge on circles of longitude or latitude (can be used to register reduced gaussion grids)
  (yac_cdef_grid_unstruct_ll)
• adds check which ensures that the entries in the cell_to_vertex array in the definition of unstructed grids are within the valid range

Version 3.0.0 (Mar 2023)

• various fixes
• various improvements in configure environment
• source to target point mapping now applies spread distance to distance between target points and to bounding circles of target cells
• updates libmtime to version 1.1.1
• new configuration file format
  • use of YAML or JSON instead of XML
  • reduction of information in configuration file
• reduction in and changes to initialisation routines
  • does not take configuration as input anymore
  • replaces group communicator concept with MPI handshake algorithm
• various changes and renaming of interfaces
  • yac_cget_localcomm -> yac_cget_comp_comm
  • yac_cget_pair_rootcomm -> yac_cget_comps_comm
  • yac_csearch -> yac_cenddef
  • yac_r4_ptr -> yac_real_ptr
  • yac_r8_ptr -> yac_dble_ptr
• new interfaces for
  • reading configuration files
    • contents of configuration file is added directly to local configuration
    • possibility to read multiple configuration files
  • definition of calendar (can be set in configuration file and/or through interface)
  • synchronisation of coupling configuration between processes
  • querying coupling configuration of remote components
  • definition of couples in definition phase
  • definition of metadata for components, grids, and fields that can be queried by all processes after synchronisation of definitions
  • emitting coupling configuration at the end of the definition phase
• new constants in interface
  • calendar types
  • time unit types
• improvement of Python support
  • new yac::Grid::set_core_mask
  • new yac::Points::set_mask
  • improves cleanup of YAC instances
  • various minor improvements and bug fixes
• relieves rules for
  • definition of components, grids, and fields; do not have to be defined in coupling configuration anymore
  • field names of couples; source and target field names do not have to be identical anymore
• removes GUI

Version 2.6.2 (Dec 2022)

• various bug fixes
• new constants for the role of a field (YAC_EXCHANGE_TYPE_NONE, YAC_EXCHANGE_TYPE_SOURCE, YAC_EXCHANGE_TYPE_TARGET)
• put operation now informs the user if the provided data was used in a reduction operation (e.g. accumulate or average) and not sent to any other component
• adds new inquiry interface which informs about the action a put/get will perform (yac_cget_action and yac_fget_action)
• adds interface that allows skipping a put/get call if the action would have been YAC_ACTION_NONE (yac_cupdate and yac_fupdate)
• reworks overlap computation between cells center point for concave cells is not needed anymore better support for concave cells

Version 2.6.1 (Sep 2022)

• adds Python bindings
• adds new time operation YAC_REDUCTION_TIME_MINIMUM and YAC_REDUCTION_TIME_MAXIMUM
• various improvements in configure environment
• adds configure-time check for faulty MPICH versions (#6083)
• some minor fixes

Version 2.6.0 (Aug 2022)

• adds constants returned via info argument by yac_cput and yac_cget to interface (YAC_ACTION_NONE, YAC_ACTION_COUPLING, YAC_ACTION_GET_FOR_RESTART, YAC_ACTION_PUT_FOR_RESTART, and YAC_ACTION_OUT_OF_BOUND)
• adds constants for time operation types to interface (YAC_REDUCTION_INSTANT, YAC_REDUCTION_ACCUMULATE, and YAC_REDUCTION_TIME_AVERAGE)
• adds check to YAC initialisation, which check whether all components in a run have been compiled with the same YAC version
• adds new interface for curvilinear grids (yac_cdef_grid_curve2d and yac_cdef_points_curve2d)
• adds new interfaces for generating a coupling configuration at runtime
• adds new YAC initialisation interfaces that accept a coupling configuration instead of an XML file (yac_cinit_couple_config, yac_cinit_couple_config_group, yac_cinit_couple_config_instance, yac_cinit_couple_config_group_instance, yac_cinit_couple_config_comm, yac_cinit_couple_config_comm_group, yac_cinit_couple_config_comm_instance, and yac_cinit_couple_config_comm_group_instance)
• adds new interpolation User callback interpolation

Version 2.5.2 (Jun 2022)

• some fixes

Version 2.5.1 (Jun 2022)

• adds new query routine for fields (yac_cget_collection_size_id, yac_cget_collection_size_name, yac_cget_collection_size_name_instance)
• adds optional maximum search distance to interpolation method Source to Target mapping
• adds support for regular Gaussian grids to weights2vtk tool
• some bug fixes

Version 2.5.0 (May 2022)

• adds new YAC initialisation interface that allows an early splitting of of the MPI_COMM_WORLD before the definition of components (yac_cinit_group, yac_cinit_group_instance, yac_cinit_comm_group, yac_cinit_comm_group_instance, yac_cget_groupcomm, yac_cget_groupcomm_instance, yac_finit_group, yac_finit_group_instance, yac_finit_comm_group, yac_finit_comm_group_instance, yac_fget_groupcomm, and yac_fget_groupcomm_instance)
• adds new query routines for coupling configuration (yac_get_transients_count, yac_get_transient_ids, yac_is_transient_source, yac_is_transient_target, yac_get_transient_collection_size, yac_get_transient_coupling_period, yac_get_transient_source_grid_name, yac_get_transient_source_grid_name, yac_fget_transients_count, yac_fget_transient_ids, yac_fis_transient_source, yac_fis_transient_target, yac_fget_transient_collection_size, yac_fget_transient_coupling_period, yac_fget_transient_source_grid_name, yac_fget_transient_target_grid_name, and yac_fget_transient_name)

Version 2.4.3 (May 2022)

• multiple source fields per target field are now supported in YAC2
• rework of intersection computation and clipping for better and more consistent results
• new query routines for fields (yac_cget_field_id_from_field_and_grid_name, yac_cget_field_id_from_field_and_grid_name_instance, yac_cget_role_of_field_by_field_and_grid_name, and yac_cget_role_of_field_by_field_and_grid_name_instance)
• added support for multi precision library in case the hardware does not support a double precision data type with more than 64 Bit
• significant improvment of test coverage and as a result a lot of fixes

Version 2.4.2 (Dec 2021)

• fixes bug which cause a segmentation fault in case the configuration XML file did not contain a transient_grid_refs section for a component
• improves computation of barycenters (relevant for 2nd order conservative interpolation)
• fixes bug that occured the core mask for a cell, vertex, or edge was 0 on all processes
• fixes issue that occured if a process with no cells was part of a active component
• additional code cleanup and improved testing

Version 2.4.1 (Dec 2021)

• some change to configure to avoid issues caused by ICON build process

Version 2.4.0 (Nov 2021)

• rework of internal handling of coupling configurations
• new dummy initialisation routines for YAC (yac_cinit_dummy, yac_cinit_comm_dummy, yac_finit_dummy)
• additional documentation on YAC instances
• automatic unit tests by gitlab CI
• automatic test coverage report by gitlab CI
• improved test coverage
• a lot of code cleanup
• fixes issue with weight files that contained more than one fixed value
• fixes broken accumulation time opertion of put
• some additional minor fixes

Version 2.3.2 (Sep 2021)

• adds some workaround for NEC compiler
• grids and points are now independent of YAC instances (a grid defined once can be used by multiple YAC instances)
• some bug fixes

Version 2.3.1 (Sep 2021)

• some bug fixes

Version 2.3.0 (Aug 2021)

• improved doxygen documentation (Interpolation, documentation of XML configuration file)
• new interpolation: creep fill (Creep Fill)
• support for restarting of YAC (Restarting YAC)
• new interface that cleans up YAC without finalising MPI, which is required for restarting (yac_ccleanup and yac_fcleanup)
• new interface that allow YAC to be initialised with MPI communicator other than MPI_COMM_WORLD (yac_cinit_comm and yac_finit_comm)
• libxml2 is now a mandatory requirement for YAC
• reduces number of arguments to yac_csearch and yac_fsearch
• support for multiple YAC instances in parallel
• new interfaces for working with multiple YAC instances (yac_cinit_instance, yac_cinit_comm_instance, yac_ccleanup_instance, yac_cfinalize_instance, yac_cdef_datetime_instance, yac_cdef_comp_instance, yac_cdef_comps_instance, yac_cget_pair_rootcomm_instance, yac_cdef_grid_reg2d_instance, yac_cdef_grid_unstruct_instance, yac_csearch_instance, yac_get_start_datetime_instance, yac_get_end_datetime_instance, yac_cget_nbr_fields_instance, yac_cget_field_ids_instance, yac_cget_field_id_from_name_instance, yac_cget_role_of_field_by_name_instance, yac_cget_coupling_timestep_name_instance, yac_cget_model_timestep_name_instance, and Fortran counterparts)
• removes grid_id from def_field interfaces (yac_cdef_field, yac_cdef_field_mask, yac_fdef_field, and yac_fdef_field_mask)
• various bug fixes

Version 2.2.0 (May 2021)

• put/get now work on processes that are both source an target
• adds new interface yac_cexchange (yac_fexchange)

Version 2.1.2 (Apr 2021)

• interpolation method "Source Point Mapping" now has the option to distribute the source data to multiple target cell within a spread distance, which can be set by the user
• interpolation method "Average" now has a new barycentric coordiante based weighting option
• fixes issue that occured, when creating distributed grids on a single process

Version 2.1.1 (Mar 2021)

• a lot of cleanup and refactoring
• small bug fixes

Version 2.1.0 (Feb 2021)

• new interface for mask handling (yac_cdef_mask and yac_cdef_field_mask)
• fixes in dist_grid and conservative interpolation

Version 2.0.1 (Jan 2021)

• Support for user file interpolation

Version 2.0.0 (Jan 2021)

• Internal rewrite
• Clean-up of coupling xml and GUI

Version 1.5.5 (Aug 2020)

• YAC is now shipped with BSD license
• minor bug fixes
• update to latest version of mtime

Version 1.5.4 (Dec 2019)

• Arguments '–with-regard-for-quality' and '–with-mpi-pack-external' are renamed to '–enable-mpi-checks' and '–enable-mpi-pack-external' respectively. Configure-time checks related to MPI_Pack_external are run only when the usage of MPI_Pack_external is enabled.
• Influential environment variables '*_C_INCLUDE' and '*_C_LIB' are renamed to '*_CFLAGS' and '*_CLIBS' respectively. When set, the values of the variables override the values set with '–with-*-root', '–with-*-include', and '-with-*-lib'.
• The default subdirectory to be searched for libxml2 header files is switched from '$with_xml2_root/include' to 'XML2_ROOT/include/libxml2'.
• Automatic update of LD_LIBRARY_PATH when running the test suite on Linux (no need to specify rpath flags at configure-time anymore).
• cfortran.h is not used anymore and removed from the repository. The name-mangling scheme required to enable Fortran backend for LAPACK is detected at configure-time.
• The configure script generates a public header file 'yac_config.h' (installed to $prefix/include), which can be used by user applications to check for features enabled in YAC. The file can be safely included by Fortran compilers as well.
• Silent mode for 'make' is enabled by default (can be overridden at the configure time with the option '–disable-silent-rules' or at the build time with the argument V=1, e.g. 'make V=1')
• The configure script does not try to guess which libraries are required to enable MPI: users are encouraged to use MPI compiler wrappers).
• Minor improvements for 'make clean' and 'make distclean' commands.
• MPI_LAUNCH variable can be now set without the absolute path prefix.

Version 1.5.3 (Nov 2019)

• bug fix in interpolation method spmap

Version 1.5.2 (Jul 2019)

• bug fix in interpolation method spmap
• error checking for all allocation routines
• new configure test for bug in cray-mpich

Version 1.5.1 (Jun 2019)

• gauss weighted distance n-nearest neighbours
• bug fix to prevent a segmentation fault in nnn_search_local, if the number of unmasked point on a process is zero

Version 1.5.0 (Feb 2019)

• a frist implementation of interpolation with radial basis functions (experimental)
• refactoring of configure
• refactoring of internal routines and structs
• bug fixes

Version 1.4.0 (22 Oct 2018)

• new interpolation: 2nd order conservative remapping
• optimisation
• fixes of memory leaks in tests and examples
• cleaning of examples

Version 1.3.2 (21 Aug 2018)

• internally coordinates are now handled in the cartesian space to avoid unneccessary forward- and backward conversion
• improved performance for nearest-neighbour search
• bug fixes and cleanup

Version 1.3.1 (6 Aug 2018)

• new interpolation: hybrid cubic spherical Bernstern-Bezier
• optimisation
• bug fixes

Version 1.3.0 (25 Sep 2017)

• new features in user interface:
  • optional mapping of interpolated data on the target instead of source processes
  • couple_config (yac_setup_couple_config) now supports coupling of domains located on the same process
  • extension of the user interface by yac_cdef_comps and yac_fdef_comps
  • example based on OASIS_MCT paper (Craig et al, 2017), their Fig. 1 (see https://www.geosci-model-dev-discuss.net/gmd-2017-64/)
  • interface yac_fdef_field_nomask
  • support of ISO format for time steps and coupling period
  • constants for location of data points YAC_LOCATION_CELL, YAC_LOCATION_CORNER and YAC_LOCATION_EDGE
  • interface yac_fset_comp_io_proc_step and yac_fget_comp_io_proc_step
  • interface.h renamed to yac_interface.h
  • interpolation method file now read point location from weight file
  • interpolation method file now supports fixed values
• new internal features:
  • point_sphere_part_search for optimised search in source point mapping (spmap) and n nearest neighbour (nnn)
  • interpolation plan type pointsum
  • interpolation plan type point for special case of 1 nearest neighbour
  • yac_comm_bsend now integrated into communicator_mpi to allow for waiting of bsends to be completed (results in performance improvements)
  • parallel reading of grid files especially required for high resolution grids like R02B11 (yac_read_icon_grid_information_parallel)
  • experimental new interpolation methods smoothed patch recovery
  • new communication routines yac_comm_isend, yac_comm_irecv, yac_comm_testsome, yac_comm_waitall, yac_comm_free_request, yac_comm_scatter_callback and yac_comm_reduce_callback
  • yac_comm_check can now be used to pass on control to communication from time to time when processes a kept busy with huge but low-priority tasks, used in conserv, nnn, and patch.
  • DEBUG_TAGS prints tags and their associated strings
  • ATLAS is now supported by configure
  • component now contains information on good IO-processor count used for reading and writing weight files
  • collective routine yac_get_unique_comm_tags as a replacement for yac_get_unique_comm_tag which was unsave to use
  • constructor yac_global_search_all_local_new
  • constructor yac_new_field_interpolation_gen_src_tgt_2
• bug fixes:
  • rewrite of spmap to overcome various problems
  • writing out weight files: older versions ignore writing out of some files
  • ensure bit-reproducability for conservative remapping and nearest-neighbour interpolation
  • useless use statements in Fortran interface removed
• new interpolation method spmap (source point mapping); maps all non-masked source points to the nearest target point
  • with example toy_icon_runoff_atm/ocn to investigate spmap for icon grids
• rework of n nearest neighbour interpolation method; much faster and less complex communication scheme
• significant performance improvement in sphere part
• removing of unused functions and variables
• autotools update
• update of GUI manual
• update to latest version of mtime
• cleaner handling of timestep and timelag in the GUI
• makes write_restart and debug_mode optional in xml
• components now can share one, some or all processes

Version 1.2.0 (30 Nov 2015)

• bug fixes and performance improvements for reading in weights from files

Version 1.1.0 (28 Oct 2015)

• first complete version of the GUI
• reduction of MPI messages by using asynchronous collective operations
• performance improvements in couple_config and global search
• fix of several memory leaks
• replaces mpi_pack, mpi_unpack, mpi_pack_size with its external counterpart
• weighted average
• correct behaviour or redirect stdout

Version 1.0.5 (22 Jul 2015)

• performance improvements for search
• fix in Fortran interface for yac_fget
• minor bug fixes

Version 1.0.4 (9 Jun 2015)

• major update of GUI with improved functionality
• support user defined weights added (writing and reading of weight files)
• load balancing functionality added
• send/receive of individual collections/bundles with one operation
• cubed sphere test case
• minor bug fixes, performance improvements and code cleaning

Version 1.0.3 (5 Feb 2015)

• priority given to targets sending grid info to source processes (see commit 92ee8eb6)
• yac_ prefix for all external symbols
• update of GUI plus minor revision of coupling.xsd
• first version of GUI user manual

Version 1.0.2 (30 Oct 2014)

• users are allowed to pass job start/end dates via F90/C API
• new toy example to read in World Ocean Atlas 2009 data
• bug fixes

Version 1.0.1 (3 Sep 2014)

SAB 2014 version

• interpolation weights are now calculated only once if the same interpolation stack is applied to more than field, provided that grid- and mask-pairs are identical as well
• some communication is saved for conservative remapping and patch recovery by packing data into a single message
• support for moderately concave cells
• distance-weighted n-nearest-neighbour interpolation
• old simple n-nearest-neighbour weights are now optional

Version 1.0.0 (22 Jul 2014)

• first release