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