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