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