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