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