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