1# Changes/Release Notes 2 3On this page we provide a summary of the main API changes, new features and examples for each release of libCEED. 4 5(main)= 6 7## Current `main` branch 8 9### Interface changes 10 11- Update `CeedOperatorContext*` functions to `CeedOperator*Context*` functions for consistency. 12For example, `CeedOperatorContextGetFieldLabel` was renamed to `CeedOperatorGetContextFieldLabel`. 13 14### New features 15 16- Added {c:func}`CeedOperatorGetFieldByName` to access a specific `CeedOperatorField` by its name 17- Update `/cpu/self/memcheck/*` backends to help verify `CeedVector` array access assumptions and `CeedQFunction` user output assumptions. 18- Update {c:func}`CeedOperatorLinearAssembleDiagonal` to provide default implementation that supports `CeedOperator` with multiple active bases. 19- Added Sycl backends `/gpu/sycl/ref` and `/gpu/sycl/shared` 20- Added {c:func}`CeedBasisApplyAtPoints` for evalution of values and derivaties at arbitrary points inside elements 21 22### Examples 23 24#### {ref}`example-petsc-bps` 25 26- Requires PETSc version 3.19 or later 27 28(v0-11)= 29 30## v0.11 (Dec 24, 2022) 31 32### Interface changes 33 34- Added {c:func}`CeedOperatorSetName` for more readable {c:func}`CeedOperatorView` output. 35- Added {c:func}`CeedBasisCreateProjection` to facilitate interpolation between nodes for separate `CeedBases`. 36- Rename and move {c:func}`CeedCompositeOperatorGetNumSub` and {c:func}`CeedCompositeOperatorGetSubList` to public interface. 37 38### New features 39 40- Update `/cpu/self/memcheck/*` backends to help verify `CeedQFunctionContext` data sizes provided by user. 41- Improved support for $H(\text{div})$ bases. 42- Added `CeedInt_FMT` to support potential future use of larger integer sizes. 43- Added `CEED_QFUNCTION_ATTR` for setting compiler attributes/pragmas to `CEED_QFUNCTION_HELPER` and `CEED_QFUNCTION`. 44- OCCA backend updated to latest OCCA release; DPC++ and OMP OCCA modes enabled. 45Due to a limitation of the OCCA parser, typedefs are required to use pointers to arrays in QFunctions with the OCCA backend. 46This issue will be fixed in a future OCCA release. 47 48### Bugfix 49 50- Fix bug in setting device id for GPU backends. 51- Fix storing of indices for `CeedElemRestriction` on the host with GPU backends. 52- Fix `CeedElemRestriction` sizing for {c:func}`CeedOperatorAssemblePointBlockDiagonal`. 53- Fix bugs in CPU implementation of {c:func}`CeedOperatorLinearAssemble` when there are different number of active input modes and active output modes. 54 55### Examples 56 57#### {ref}`example-petsc-navier-stokes` 58 59- Various performance enhancements, analytic matrix-free and assembled Jacobian, and PETSc solver configurations for GPUs. 60- Refactored to improve code reuse and modularity. 61- Support for primitive variables for more accurate boundary layers and all-speed flow. 62- Added $YZ\beta$ shock capturing scheme and Shock Tube example. 63- Added Channel example, with comparison to analytic solutions. 64- Added Flat Plate with boundary layer mesh and compressible Blasius inflow condition based on Chebyshev collocation solution of the Blasius equations. 65- Added strong and weak synthetic turbulence generation (STG) inflow boundary conditions. 66- Added "freestream" boundary conditions based on HLLC Riemann solver. 67- Automated stabilization coefficients for different basis degree. 68 69#### {ref}`example-petsc-bps` 70 71- Support for convergence studies. 72 73### Maintainability 74 75- Refactored `/gpu/cuda/shared` and `/gpu/cuda/gen` as well as `/gpu/hip/shared` and `/gpu/hip/gen` backend to improve maintainablity and reduce duplicated code. 76- Enabled support for `p > 8` for `/gpu/*/shared` backends. 77- Switch to `clang-format` over `astyle` for automatic formatting; Makefile command changed to `make format` from `make style`. 78- Improved test harness. 79 80(v0-10-1)= 81 82## v0.10.1 (Apr 11, 2022) 83 84### Interface changes 85 86- Added {c:func}`CeedQFunctionSetUserFlopsEstimate` and {c:func}`CeedOperatorGetFlopsEstimate` to facilitate estimating FLOPs in operator application. 87 88### New features 89 90- Switched MAGMA backends to use runtime compilation for tensor basis kernels (and element restriction kernels, in non-deterministic `/gpu/*/magma` backends). 91This reduces time to compile the library and increases the range of parameters for which the MAGMA tensor basis kernels will work. 92 93### Bugfix 94 95- Install JiT source files in install directory to fix GPU functionality for installed libCEED. 96 97(v0-10)= 98 99## v0.10 (Mar 21, 2022) 100 101### Interface changes 102 103- Update {c:func}`CeedQFunctionGetFields` and {c:func}`CeedOperatorGetFields` to include number of fields. 104- Promote to the public API: QFunction and Operator field objects, `CeedQFunctionField` and `CeedOperatorField`, and associated getters, {c:func}`CeedQFunctionGetFields`; {c:func}`CeedQFunctionFieldGetName`; {c:func}`CeedQFunctionFieldGetSize`; {c:func}`CeedQFunctionFieldGetEvalMode`; {c:func}`CeedOperatorGetFields`; {c:func}`CeedOperatorFieldGetElemRestriction`; {c:func}`CeedOperatorFieldGetBasis`; and {c:func}`CeedOperatorFieldGetVector`. 105- Clarify and document conditions where `CeedQFunction` and `CeedOperator` become immutable and no further fields or suboperators can be added. 106- Add {c:func}`CeedOperatorLinearAssembleQFunctionBuildOrUpdate` to reduce object creation overhead in assembly of CeedOperator preconditioning ingredients. 107- Promote {c:func}`CeedOperatorCheckReady`to the public API to facilitate interactive interfaces. 108- Warning added when compiling OCCA backend to alert users that this backend is experimental. 109- `ceed-backend.h`, `ceed-hash.h`, and `ceed-khash.h` removed. Users should use `ceed/backend.h`, `ceed/hash.h`, and `ceed/khash.h`. 110- Added {c:func}`CeedQFunctionGetKernelName`; refactored {c:func}`CeedQFunctionGetSourcePath` to exclude function kernel name. 111- Clarify documentation for {c:func}`CeedVectorTakeArray`; this function will error if {c:func}`CeedVectorSetArray` with `copy_mode == CEED_USE_POINTER` was not previously called for the corresponding `CeedMemType`. 112- Added {c:func}`CeedVectorGetArrayWrite` that allows access to uninitalized arrays; require initalized data for {c:func}`CeedVectorGetArray`. 113- Added {c:func}`CeedQFunctionContextRegisterDouble` and {c:func}`CeedQFunctionContextRegisterInt32` with {c:func}`CeedQFunctionContextSetDouble` and {c:func}`CeedQFunctionContextSetInt32` to facilitate easy updating of {c:struct}`CeedQFunctionContext` data by user defined field names. 114- Added {c:func}`CeedQFunctionContextGetFieldDescriptions` to retreive user defined descriptions of fields that are registered with `CeedQFunctionContextRegister*`. 115- Renamed `CeedElemTopology` entries for clearer namespacing between libCEED enums. 116- Added type `CeedSize` equivalent to `ptrdiff_t` for array sizes in {c:func}`CeedVectorCreate`, {c:func}`CeedVectorGetLength`, `CeedElemRestrictionCreate*`, {c:func}`CeedElemRestrictionGetLVectorSize`, and {c:func}`CeedOperatorLinearAssembleSymbolic`. This is a breaking change. 117- Added {c:func}`CeedOperatorSetQFunctionUpdated` to facilitate QFunction data re-use between operators sharing the same quadrature space, such as in a multigrid hierarchy. 118- Added {c:func}`CeedOperatorGetActiveVectorLengths` to get shape of CeedOperator. 119 120### New features 121 122- `CeedScalar` can now be set as `float` or `double` at compile time. 123- Added JiT utilities in `ceed/jit-tools.h` to reduce duplicated code in GPU backends. 124- Added support for JiT of QFunctions with `#include "relative/path/local-file.h"` statements for additional local files. Note that files included with `""` are searched relative to the current file first, then by compiler paths (as with `<>` includes). To use this feature, one should adhere to relative paths only, not compiler flags like `-I`, which the JiT will not be aware of. 125- Remove need to guard library headers in QFunction source for code generation backends. 126- `CeedDebugEnv()` macro created to provide debugging outputs when Ceed context is not present. 127- Added {c:func}`CeedStringAllocCopy` to reduce repeated code for copying strings internally. 128- Added {c:func}`CeedPathConcatenate` to facilitate loading kernel source files with a path relative to the current file. 129- Added support for non-tensor H(div) elements, to include CPU backend implementations and {c:func}`CeedBasisCreateHdiv` convenience constructor. 130- Added {c:func}`CeedQFunctionSetContextWritable` and read-only access to `CeedQFunctionContext` data as an optional feature to improve GPU performance. By default, calling the `CeedQFunctionUser` during {c:func}`CeedQFunctionApply` is assumed to write into the `CeedQFunctionContext` data, consistent with the previous behavior. Note that if a user asserts that their `CeedQFunctionUser` does not write into the `CeedQFunctionContext` data, they are responsible for the validity of this assertion. 131- Added support for element matrix assembly in GPU backends. 132 133### Maintainability 134 135- Refactored preconditioner support internally to facilitate future development and improve GPU completeness/test coverage. 136- `Include-what-you-use` makefile target added as `make iwyu`. 137- Create backend constant `CEED_FIELD_MAX` to reduce magic numbers in codebase. 138- Put GPU JiTed kernel source code into separate files. 139- Dropped legacy version support in PETSc based examples to better utilize PETSc DMPlex and Mat updates to support libCEED; current minimum PETSc version for the examples is v3.17. 140 141(v0-9)= 142 143## v0.9 (Jul 6, 2021) 144 145### Interface changes 146 147- Minor modification in error handling macro to silence pedantic warnings when compiling with Clang, but no functional impact. 148 149### New features 150 151- Add {c:func}`CeedVectorAXPY` and {c:func}`CeedVectorPointwiseMult` as a convenience for stand-alone testing and internal use. 152- Add `CEED_QFUNCTION_HELPER` macro to properly annotate QFunction helper functions for code generation backends. 153- Add `CeedPragmaOptimizeOff` macro for code that is sensitive to floating point errors from fast math optimizations. 154- Rust support: split `libceed-sys` crate out of `libceed` and [publish both on crates.io](https://crates.io/crates/libceed). 155 156### Performance improvements 157 158### Examples 159 160- Solid mechanics mini-app updated to explore the performance impacts of various formulations in the initial and current configurations. 161- Fluid mechanics example adds GPU support and improves modularity. 162 163### Deprecated backends 164 165- The `/cpu/self/tmpl` and `/cpu/self/tmpl/sub` backends have been removed. These backends were intially added to test the backend inheritance mechanism, but this mechanism is now widely used and tested in multiple backends. 166 167(v0-8)= 168 169## v0.8 (Mar 31, 2021) 170 171### Interface changes 172 173- Error handling improved to include enumerated error codes for C interface return values. 174- Installed headers that will follow semantic versioning were moved to {code}`include/ceed` directory. These headers have been renamed from {code}`ceed-*.h` to {code}`ceed/*.h`. Placeholder headers with the old naming schema are currently provided, but these headers will be removed in the libCEED v0.9 release. 175 176### New features 177 178- Julia and Rust interfaces added, providing a nearly 1-1 correspondence with the C interface, plus some convenience features. 179- Static libraries can be built with `make STATIC=1` and the pkg-config file is installed accordingly. 180- Add {c:func}`CeedOperatorLinearAssembleSymbolic` and {c:func}`CeedOperatorLinearAssemble` to support full assembly of libCEED operators. 181 182### Performance improvements 183 184- New HIP MAGMA backends for hipMAGMA library users: `/gpu/hip/magma` and `/gpu/hip/magma/det`. 185- New HIP backends for improved tensor basis performance: `/gpu/hip/shared` and `/gpu/hip/gen`. 186 187### Examples 188 189- {ref}`example-petsc-elasticity` example updated with traction boundary conditions and improved Dirichlet boundary conditions. 190- {ref}`example-petsc-elasticity` example updated with Neo-Hookean hyperelasticity in current configuration as well as improved Neo-Hookean hyperelasticity exploring storage vs computation tradeoffs. 191- {ref}`example-petsc-navier-stokes` example updated with isentropic traveling vortex test case, an analytical solution to the Euler equations that is useful for testing boundary conditions, discretization stability, and order of accuracy. 192- {ref}`example-petsc-navier-stokes` example updated with support for performing convergence study and plotting order of convergence by polynomial degree. 193 194(v0-7)= 195 196## v0.7 (Sep 29, 2020) 197 198### Interface changes 199 200- Replace limited {code}`CeedInterlaceMode` with more flexible component stride {code}`compstride` in {code}`CeedElemRestriction` constructors. 201 As a result, the {code}`indices` parameter has been replaced with {code}`offsets` and the {code}`nnodes` parameter has been replaced with {code}`lsize`. 202 These changes improve support for mixed finite element methods. 203- Replace various uses of {code}`Ceed*Get*Status` with {code}`Ceed*Is*` in the backend API to match common nomenclature. 204- Replace {code}`CeedOperatorAssembleLinearDiagonal` with {c:func}`CeedOperatorLinearAssembleDiagonal` for clarity. 205- Linear Operators can be assembled as point-block diagonal matrices with {c:func}`CeedOperatorLinearAssemblePointBlockDiagonal`, provided in row-major form in a {code}`ncomp` by {code}`ncomp` block per node. 206- Diagonal assemble interface changed to accept a {ref}`CeedVector` instead of a pointer to a {ref}`CeedVector` to reduce memory movement when interfacing with calling code. 207- Added {c:func}`CeedOperatorLinearAssembleAddDiagonal` and {c:func}`CeedOperatorLinearAssembleAddPointBlockDiagonal` for improved future integration with codes such as MFEM that compose the action of {ref}`CeedOperator`s external to libCEED. 208- Added {c:func}`CeedVectorTakeAray` to sync and remove libCEED read/write access to an allocated array and pass ownership of the array to the caller. 209 This function is recommended over {c:func}`CeedVectorSyncArray` when the {code}`CeedVector` has an array owned by the caller that was set by {c:func}`CeedVectorSetArray`. 210- Added {code}`CeedQFunctionContext` object to manage user QFunction context data and reduce copies between device and host memory. 211- Added {c:func}`CeedOperatorMultigridLevelCreate`, {c:func}`CeedOperatorMultigridLevelCreateTensorH1`, and {c:func}`CeedOperatorMultigridLevelCreateH1` to facilitate creation of multigrid prolongation, restriction, and coarse grid operators using a common quadrature space. 212 213### New features 214 215- New HIP backend: `/gpu/hip/ref`. 216- CeedQFunction support for user `CUfunction`s in some backends 217 218### Performance improvements 219 220- OCCA backend rebuilt to facilitate future performance enhancements. 221- Petsc BPs suite improved to reduce noise due to multiple calls to {code}`mpiexec`. 222 223### Examples 224 225- {ref}`example-petsc-elasticity` example updated with strain energy computation and more flexible boundary conditions. 226 227### Deprecated backends 228 229- The `/gpu/cuda/reg` backend has been removed, with its core features moved into `/gpu/cuda/ref` and `/gpu/cuda/shared`. 230 231(v0-6)= 232 233## v0.6 (Mar 29, 2020) 234 235libCEED v0.6 contains numerous new features and examples, as well as expanded 236documentation in [this new website](https://libceed.org). 237 238### New features 239 240- New Python interface using [CFFI](https://cffi.readthedocs.io/) provides a nearly 241 1-1 correspondence with the C interface, plus some convenience features. For instance, 242 data stored in the {cpp:type}`CeedVector` structure are available without copy as 243 {py:class}`numpy.ndarray`. Short tutorials are provided in 244 [Binder](https://mybinder.org/v2/gh/CEED/libCEED/main?urlpath=lab/tree/examples/tutorials/). 245- Linear QFunctions can be assembled as block-diagonal matrices (per quadrature point, 246 {c:func}`CeedOperatorAssembleLinearQFunction`) or to evaluate the diagonal 247 ({c:func}`CeedOperatorAssembleLinearDiagonal`). These operations are useful for 248 preconditioning ingredients and are used in the libCEED's multigrid examples. 249- The inverse of separable operators can be obtained using 250 {c:func}`CeedOperatorCreateFDMElementInverse` and applied with 251 {c:func}`CeedOperatorApply`. This is a useful preconditioning ingredient, 252 especially for Laplacians and related operators. 253- New functions: {c:func}`CeedVectorNorm`, {c:func}`CeedOperatorApplyAdd`, 254 {c:func}`CeedQFunctionView`, {c:func}`CeedOperatorView`. 255- Make public accessors for various attributes to facilitate writing composable code. 256- New backend: `/cpu/self/memcheck/serial`. 257- QFunctions using variable-length array (VLA) pointer constructs can be used with CUDA 258 backends. (Single source is coming soon for OCCA backends.) 259- Fix some missing edge cases in CUDA backend. 260 261### Performance Improvements 262 263- MAGMA backend performance optimization and non-tensor bases. 264- No-copy optimization in {c:func}`CeedOperatorApply`. 265 266### Interface changes 267 268- Replace {code}`CeedElemRestrictionCreateIdentity` and 269 {code}`CeedElemRestrictionCreateBlocked` with more flexible 270 {c:func}`CeedElemRestrictionCreateStrided` and 271 {c:func}`CeedElemRestrictionCreateBlockedStrided`. 272- Add arguments to {c:func}`CeedQFunctionCreateIdentity`. 273- Replace ambiguous uses of {cpp:enum}`CeedTransposeMode` for L-vector identification 274 with {cpp:enum}`CeedInterlaceMode`. This is now an attribute of the 275 {cpp:type}`CeedElemRestriction` (see {c:func}`CeedElemRestrictionCreate`) and no 276 longer passed as `lmode` arguments to {c:func}`CeedOperatorSetField` and 277 {c:func}`CeedElemRestrictionApply`. 278 279### Examples 280 281libCEED-0.6 contains greatly expanded examples with {ref}`new documentation <Examples>`. 282Notable additions include: 283 284- Standalone {ref}`ex2-surface` ({file}`examples/ceed/ex2-surface`): compute the area of 285 a domain in 1, 2, and 3 dimensions by applying a Laplacian. 286 287- PETSc {ref}`example-petsc-area` ({file}`examples/petsc/area.c`): computes surface area 288 of domains (like the cube and sphere) by direct integration on a surface mesh; 289 demonstrates geometric dimension different from topological dimension. 290 291- PETSc {ref}`example-petsc-bps`: 292 293 - {file}`examples/petsc/bpsraw.c` (formerly `bps.c`): transparent CUDA support. 294 - {file}`examples/petsc/bps.c` (formerly `bpsdmplex.c`): performance improvements 295 and transparent CUDA support. 296 - {ref}`example-petsc-bps-sphere` ({file}`examples/petsc/bpssphere.c`): 297 generalizations of all CEED BPs to the surface of the sphere; demonstrates geometric 298 dimension different from topological dimension. 299 300- {ref}`example-petsc-multigrid` ({file}`examples/petsc/multigrid.c`): new p-multigrid 301 solver with algebraic multigrid coarse solve. 302 303- {ref}`example-petsc-navier-stokes` ({file}`examples/fluids/navierstokes.c`; formerly 304 `examples/navier-stokes`): unstructured grid support (using PETSc's `DMPlex`), 305 implicit time integration, SU/SUPG stabilization, free-slip boundary conditions, and 306 quasi-2D computational domain support. 307 308- {ref}`example-petsc-elasticity` ({file}`examples/solids/elasticity.c`): new solver for 309 linear elasticity, small-strain hyperelasticity, and globalized finite-strain 310 hyperelasticity using p-multigrid with algebraic multigrid coarse solve. 311 312(v0-5)= 313 314## v0.5 (Sep 18, 2019) 315 316For this release, several improvements were made. Two new CUDA backends were added to 317the family of backends, of which, the new `cuda-gen` backend achieves state-of-the-art 318performance using single-source {ref}`CeedQFunction`. From this release, users 319can define Q-Functions in a single source code independently of the targeted backend 320with the aid of a new macro `CEED QFUNCTION` to support JIT (Just-In-Time) and CPU 321compilation of the user provided {ref}`CeedQFunction` code. To allow a unified 322declaration, the {ref}`CeedQFunction` API has undergone a slight change: 323the `QFunctionField` parameter `ncomp` has been changed to `size`. This change 324requires setting the previous value of `ncomp` to `ncomp*dim` when adding a 325`QFunctionField` with eval mode `CEED EVAL GRAD`. 326 327Additionally, new CPU backends 328were included in this release, such as the `/cpu/self/opt/*` backends (which are 329written in pure C and use partial **E-vectors** to improve performance) and the 330`/cpu/self/ref/memcheck` backend (which relies upon the 331[Valgrind](http://valgrind.org/) Memcheck tool to help verify that user 332{ref}`CeedQFunction` have no undefined values). 333This release also included various performance improvements, bug fixes, new examples, 334and improved tests. Among these improvements, vectorized instructions for 335{ref}`CeedQFunction` code compiled for CPU were enhanced by using `CeedPragmaSIMD` 336instead of `CeedPragmaOMP`, implementation of a {ref}`CeedQFunction` gallery and 337identity Q-Functions were introduced, and the PETSc benchmark problems were expanded 338to include unstructured meshes handling were. For this expansion, the prior version of 339the PETSc BPs, which only included data associated with structured geometries, were 340renamed `bpsraw`, and the new version of the BPs, which can handle data associated 341with any unstructured geometry, were called `bps`. Additionally, other benchmark 342problems, namely BP2 and BP4 (the vector-valued versions of BP1 and BP3, respectively), 343and BP5 and BP6 (the collocated versions---for which the quadrature points are the same 344as the Gauss Lobatto nodes---of BP3 and BP4 respectively) were added to the PETSc 345examples. Furthermoew, another standalone libCEED example, called `ex2`, which 346computes the surface area of a given mesh was added to this release. 347 348Backends available in this release: 349 350| CEED resource (`-ceed`) | Backend | 351|--------------------------|-----------------------------------------------------| 352| `/cpu/self/ref/serial` | Serial reference implementation | 353| `/cpu/self/ref/blocked` | Blocked reference implementation | 354| `/cpu/self/ref/memcheck` | Memcheck backend, undefined value checks | 355| `/cpu/self/opt/serial` | Serial optimized C implementation | 356| `/cpu/self/opt/blocked` | Blocked optimized C implementation | 357| `/cpu/self/avx/serial` | Serial AVX implementation | 358| `/cpu/self/avx/blocked` | Blocked AVX implementation | 359| `/cpu/self/xsmm/serial` | Serial LIBXSMM implementation | 360| `/cpu/self/xsmm/blocked` | Blocked LIBXSMM implementation | 361| `/cpu/occa` | Serial OCCA kernels | 362| `/gpu/occa` | CUDA OCCA kernels | 363| `/omp/occa` | OpenMP OCCA kernels | 364| `/ocl/occa` | OpenCL OCCA kernels | 365| `/gpu/cuda/ref` | Reference pure CUDA kernels | 366| `/gpu/cuda/reg` | Pure CUDA kernels using one thread per element | 367| `/gpu/cuda/shared` | Optimized pure CUDA kernels using shared memory | 368| `/gpu/cuda/gen` | Optimized pure CUDA kernels using code generation | 369| `/gpu/magma` | CUDA MAGMA kernels | 370 371Examples available in this release: 372 373:::{list-table} 374:header-rows: 1 375:widths: auto 376* - User code 377 - Example 378* - `ceed` 379 - * ex1 (volume) 380 * ex2 (surface) 381* - `mfem` 382 - * BP1 (scalar mass operator) 383 * BP3 (scalar Laplace operator) 384* - `petsc` 385 - * BP1 (scalar mass operator) 386 * BP2 (vector mass operator) 387 * BP3 (scalar Laplace operator) 388 * BP4 (vector Laplace operator) 389 * BP5 (collocated scalar Laplace operator) 390 * BP6 (collocated vector Laplace operator) 391 * Navier-Stokes 392* - `nek5000` 393 - * BP1 (scalar mass operator) 394 * BP3 (scalar Laplace operator) 395::: 396 397(v0-4)= 398 399## v0.4 (Apr 1, 2019) 400 401libCEED v0.4 was made again publicly available in the second full CEED software 402distribution, release CEED 2.0. This release contained notable features, such as 403four new CPU backends, two new GPU backends, CPU backend optimizations, initial 404support for operator composition, performance benchmarking, and a Navier-Stokes demo. 405The new CPU backends in this release came in two families. The `/cpu/self/*/serial` 406backends process one element at a time and are intended for meshes with a smaller number 407of high order elements. The `/cpu/self/*/blocked` backends process blocked batches of 408eight interlaced elements and are intended for meshes with higher numbers of elements. 409The `/cpu/self/avx/*` backends rely upon AVX instructions to provide vectorized CPU 410performance. The `/cpu/self/xsmm/*` backends rely upon the 411[LIBXSMM](http://github.com/hfp/libxsmm) package to provide vectorized CPU 412performance. The `/gpu/cuda/*` backends provide GPU performance strictly using CUDA. 413The `/gpu/cuda/ref` backend is a reference CUDA backend, providing reasonable 414performance for most problem configurations. The `/gpu/cuda/reg` backend uses a simple 415parallelization approach, where each thread treats a finite element. Using just in time 416compilation, provided by nvrtc (NVidia Runtime Compiler), and runtime parameters, this 417backend unroll loops and map memory address to registers. The `/gpu/cuda/reg` backend 418achieve good peak performance for 1D, 2D, and low order 3D problems, but performance 419deteriorates very quickly when threads run out of registers. 420 421A new explicit time-stepping Navier-Stokes solver was added to the family of libCEED 422examples in the `examples/petsc` directory (see {ref}`example-petsc-navier-stokes`). 423This example solves the time-dependent Navier-Stokes equations of compressible gas 424dynamics in a static Eulerian three-dimensional frame, using structured high-order 425finite/spectral element spatial discretizations and explicit high-order time-stepping 426(available in PETSc). Moreover, the Navier-Stokes example was developed using PETSc, 427so that the pointwise physics (defined at quadrature points) is separated from the 428parallelization and meshing concerns. 429 430Backends available in this release: 431 432| CEED resource (`-ceed`) | Backend | 433|--------------------------|-----------------------------------------------------| 434| `/cpu/self/ref/serial` | Serial reference implementation | 435| `/cpu/self/ref/blocked` | Blocked reference implementation | 436| `/cpu/self/tmpl` | Backend template, defaults to `/cpu/self/blocked` | 437| `/cpu/self/avx/serial` | Serial AVX implementation | 438| `/cpu/self/avx/blocked` | Blocked AVX implementation | 439| `/cpu/self/xsmm/serial` | Serial LIBXSMM implementation | 440| `/cpu/self/xsmm/blocked` | Blocked LIBXSMM implementation | 441| `/cpu/occa` | Serial OCCA kernels | 442| `/gpu/occa` | CUDA OCCA kernels | 443| `/omp/occa` | OpenMP OCCA kernels | 444| `/ocl/occa` | OpenCL OCCA kernels | 445| `/gpu/cuda/ref` | Reference pure CUDA kernels | 446| `/gpu/cuda/reg` | Pure CUDA kernels using one thread per element | 447| `/gpu/magma` | CUDA MAGMA kernels | 448 449Examples available in this release: 450 451:::{list-table} 452:header-rows: 1 453:widths: auto 454* - User code 455 - Example 456* - `ceed` 457 - * ex1 (volume) 458* - `mfem` 459 - * BP1 (scalar mass operator) 460 * BP3 (scalar Laplace operator) 461* - `petsc` 462 - * BP1 (scalar mass operator) 463 * BP3 (scalar Laplace operator) 464 * Navier-Stokes 465* - `nek5000` 466 - * BP1 (scalar mass operator) 467 * BP3 (scalar Laplace operator) 468::: 469 470(v0-3)= 471 472## v0.3 (Sep 30, 2018) 473 474Notable features in this release include active/passive field interface, support for 475non-tensor bases, backend optimization, and improved Fortran interface. This release 476also focused on providing improved continuous integration, and many new tests with code 477coverage reports of about 90%. This release also provided a significant change to the 478public interface: a {ref}`CeedQFunction` can take any number of named input and output 479arguments while {ref}`CeedOperator` connects them to the actual data, which may be 480supplied explicitly to `CeedOperatorApply()` (active) or separately via 481`CeedOperatorSetField()` (passive). This interface change enables reusable libraries 482of CeedQFunctions and composition of block solvers constructed using 483{ref}`CeedOperator`. A concept of blocked restriction was added to this release and 484used in an optimized CPU backend. Although this is typically not visible to the user, 485it enables effective use of arbitrary-length SIMD while maintaining cache locality. 486This CPU backend also implements an algebraic factorization of tensor product gradients 487to perform fewer operations than standard application of interpolation and 488differentiation from nodes to quadrature points. This algebraic formulation 489automatically supports non-polynomial and non-interpolatory bases, thus is more general 490than the more common derivation in terms of Lagrange polynomials on the quadrature points. 491 492Backends available in this release: 493 494| CEED resource (`-ceed`) | Backend | 495|-------------------------|-----------------------------------------------------| 496| `/cpu/self/blocked` | Blocked reference implementation | 497| `/cpu/self/ref` | Serial reference implementation | 498| `/cpu/self/tmpl` | Backend template, defaults to `/cpu/self/blocked` | 499| `/cpu/occa` | Serial OCCA kernels | 500| `/gpu/occa` | CUDA OCCA kernels | 501| `/omp/occa` | OpenMP OCCA kernels | 502| `/ocl/occa` | OpenCL OCCA kernels | 503| `/gpu/magma` | CUDA MAGMA kernels | 504 505Examples available in this release: 506 507:::{list-table} 508:header-rows: 1 509:widths: auto 510* - User code 511 - Example 512* - `ceed` 513 - * ex1 (volume) 514* - `mfem` 515 - * BP1 (scalar mass operator) 516 * BP3 (scalar Laplace operator) 517* - `petsc` 518 - * BP1 (scalar mass operator) 519 * BP3 (scalar Laplace operator) 520* - `nek5000` 521 - * BP1 (scalar mass operator) 522 * BP3 (scalar Laplace operator) 523::: 524 525(v0-21)= 526 527## v0.21 (Sep 30, 2018) 528 529A MAGMA backend (which relies upon the 530[MAGMA](https://bitbucket.org/icl/magma) package) was integrated in libCEED for this 531release. This initial integration set up the framework of using MAGMA and provided the 532libCEED functionality through MAGMA kernels as one of libCEED’s computational backends. 533As any other backend, the MAGMA backend provides extended basic data structures for 534{ref}`CeedVector`, {ref}`CeedElemRestriction`, and {ref}`CeedOperator`, and implements 535the fundamental CEED building blocks to work with the new data structures. 536In general, the MAGMA-specific data structures keep the libCEED pointers to CPU data 537but also add corresponding device (e.g., GPU) pointers to the data. Coherency is handled 538internally, and thus seamlessly to the user, through the functions/methods that are 539provided to support them. 540 541Backends available in this release: 542 543| CEED resource (`-ceed`) | Backend | 544|-------------------------|---------------------------------| 545| `/cpu/self` | Serial reference implementation | 546| `/cpu/occa` | Serial OCCA kernels | 547| `/gpu/occa` | CUDA OCCA kernels | 548| `/omp/occa` | OpenMP OCCA kernels | 549| `/ocl/occa` | OpenCL OCCA kernels | 550| `/gpu/magma` | CUDA MAGMA kernels | 551 552Examples available in this release: 553 554:::{list-table} 555:header-rows: 1 556:widths: auto 557* - User code 558 - Example 559* - `ceed` 560 - * ex1 (volume) 561* - `mfem` 562 - * BP1 (scalar mass operator) 563 * BP3 (scalar Laplace operator) 564* - `petsc` 565 - * BP1 (scalar mass operator) 566* - `nek5000` 567 - * BP1 (scalar mass operator) 568::: 569 570(v0-2)= 571 572## v0.2 (Mar 30, 2018) 573 574libCEED was made publicly available the first full CEED software distribution, release 575CEED 1.0. The distribution was made available using the Spack package manager to provide 576a common, easy-to-use build environment, where the user can build the CEED distribution 577with all dependencies. This release included a new Fortran interface for the library. 578This release also contained major improvements in the OCCA backend (including a new 579`/ocl/occa` backend) and new examples. The standalone libCEED example was modified to 580compute the volume volume of a given mesh (in 1D, 2D, or 3D) and placed in an 581`examples/ceed` subfolder. A new `mfem` example to perform BP3 (with the application 582of the Laplace operator) was also added to this release. 583 584Backends available in this release: 585 586| CEED resource (`-ceed`) | Backend | 587|-------------------------|---------------------------------| 588| `/cpu/self` | Serial reference implementation | 589| `/cpu/occa` | Serial OCCA kernels | 590| `/gpu/occa` | CUDA OCCA kernels | 591| `/omp/occa` | OpenMP OCCA kernels | 592| `/ocl/occa` | OpenCL OCCA kernels | 593 594Examples available in this release: 595 596:::{list-table} 597:header-rows: 1 598:widths: auto 599* - User code 600 - Example 601* - `ceed` 602 - * ex1 (volume) 603* - `mfem` 604 - * BP1 (scalar mass operator) 605 * BP3 (scalar Laplace operator) 606* - `petsc` 607 - * BP1 (scalar mass operator) 608* - `nek5000` 609 - * BP1 (scalar mass operator) 610::: 611 612(v0-1)= 613 614## v0.1 (Jan 3, 2018) 615 616Initial low-level API of the CEED project. The low-level API provides a set of Finite 617Elements kernels and components for writing new low-level kernels. Examples include: 618vector and sparse linear algebra, element matrix assembly over a batch of elements, 619partial assembly and action for efficient high-order operators like mass, diffusion, 620advection, etc. The main goal of the low-level API is to establish the basis for the 621high-level API. Also, identifying such low-level kernels and providing a reference 622implementation for them serves as the basis for specialized backend implementations. 623This release contained several backends: `/cpu/self`, and backends which rely upon the 624[OCCA](http://github.com/libocca/occa) package, such as `/cpu/occa`, 625`/gpu/occa`, and `/omp/occa`. 626It also included several examples, in the `examples` folder: 627A standalone code that shows the usage of libCEED (with no external 628dependencies) to apply the Laplace operator, `ex1`; an `mfem` example to perform BP1 629(with the application of the mass operator); and a `petsc` example to perform BP1 630(with the application of the mass operator). 631 632Backends available in this release: 633 634| CEED resource (`-ceed`) | Backend | 635|-------------------------|---------------------------------| 636| `/cpu/self` | Serial reference implementation | 637| `/cpu/occa` | Serial OCCA kernels | 638| `/gpu/occa` | CUDA OCCA kernels | 639| `/omp/occa` | OpenMP OCCA kernels | 640 641Examples available in this release: 642 643| User code | Example | 644|-----------------------|-----------------------------------| 645| `ceed` | ex1 (scalar Laplace operator) | 646| `mfem` | BP1 (scalar mass operator) | 647| `petsc` | BP1 (scalar mass operator) | 648``` 649