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