xref: /libCEED/include/ceed.h (revision b9c05c73848caa4a8e85dca1ee63c2e7e70143c4)
1 /// Copyright (c) 2017, Lawrence Livermore National Security, LLC. Produced at
2 /// the Lawrence Livermore National Laboratory. LLNL-CODE-734707. All Rights
3 /// reserved. See files LICENSE and NOTICE for details.
4 ///
5 /// This file is part of CEED, a collection of benchmarks, miniapps, software
6 /// libraries and APIs for efficient high-order finite element and spectral
7 /// element discretizations for exascale applications. For more information and
8 /// source code availability see http://github.com/ceed.
9 ///
10 /// The CEED research is supported by the Exascale Computing Project 17-SC-20-SC,
11 /// a collaborative effort of two U.S. Department of Energy organizations (Office
12 /// of Science and the National Nuclear Security Administration) responsible for
13 /// the planning and preparation of a capable exascale ecosystem, including
14 /// software, applications, hardware, advanced system engineering and early
15 /// testbed platforms, in support of the nation's exascale computing imperative.
16 
17 /// @file
18 /// Public header for user and utility components of libCEED
19 #ifndef _ceed_h
20 #define _ceed_h
21 
22 /// @defgroup Ceed Ceed: core components
23 /// @defgroup CeedVector CeedVector: storing and manipulating vectors
24 /// @defgroup CeedElemRestriction CeedElemRestriction: restriction from local vectors to elements
25 /// @defgroup CeedBasis CeedBasis: fully discrete finite element-like objects
26 /// @defgroup CeedQFunction CeedQFunction: independent operations at quadrature points
27 /// @defgroup CeedOperator CeedOperator: composed FE-type operations on vectors
28 ///
29 /// @page FunctionCategories libCEED: Types of Functions
30 ///    libCEED provides three different header files depending upon the type of
31 ///    functions a user requires.
32 /// @section Utility Utility Functions
33 ///    These functions are intended general utilities that may be useful to
34 ///    libCEED developers and users. These functions can generally be found in
35 ///    "ceed.h".
36 /// @section Basic User Functions
37 ///    These functions are intended to be used by general users of the libCEED
38 ///    interface. These functions can generally be found in "ceed.h".
39 /// @section Advanced Backend Developer Functions
40 ///    These functions are intended to be used by backend developers of the
41 ///    libCEED interface. These functions can generally be found in
42 ///    "ceed-backend.h".
43 /// @section Developer Frontend Developer Functions
44 ///    These functions are intended to be used by frontend developers of the
45 ///    libCEED interface. These functions can generally be found in "ceed-impl.h".
46 
47 /**
48   CEED_EXTERN is used in this header to denote all publicly visible symbols.
49 
50   No other file should declare publicly visible symbols, thus it should never be
51   used outside ceed.h.
52  */
53 #ifdef __cplusplus
54 #  define CEED_EXTERN extern "C"
55 #else
56 #  define CEED_EXTERN extern
57 #endif
58 
59 #ifndef CEED_QFUNCTION
60 #define CEED_QFUNCTION(name) \
61   static const char name ## _loc[] = __FILE__ ":" #name;        \
62   static int name
63 #endif
64 
65 #ifndef CeedPragmaSIMD
66 #  if defined(__INTEL_COMPILER) &&__INTEL_COMPILER >= 900
67 #    define CeedPragmaSIMD _Pragma("simd")
68 #  elif defined(__GNUC__) && __GNUC__ >= 5
69 #    define CeedPragmaSIMD _Pragma("GCC ivdep")
70 #  elif defined(_OPENMP) && _OPENMP >= 201307 // OpenMP-4.0 (July, 2013)
71 #    define CeedPragmaSIMD _Pragma("omp simd")
72 #  else
73 #    define CeedPragmaSIMD
74 #  endif
75 #endif
76 
77 #include <assert.h>
78 #include <stdint.h>
79 #include <stddef.h>
80 #include <stdarg.h>
81 #include <stdio.h>
82 #include <stdbool.h>
83 
84 /// We can discuss ways to avoid forcing these to be compile-time decisions,
85 ///   but let's leave that for later.
86 /// Integer type, used for indexing
87 /// @ingroup Ceed
88 typedef int32_t CeedInt;
89 /// Scalar (floating point) type
90 /// @ingroup Ceed
91 typedef double CeedScalar;
92 
93 /// Library context created by CeedInit()
94 /// @ingroup Ceed
95 typedef struct Ceed_private *Ceed;
96 /// Non-blocking Ceed interfaces return a CeedRequest.
97 /// To perform an operation immediately, pass \ref CEED_REQUEST_IMMEDIATE instead.
98 /// @ingroup Ceed
99 typedef struct CeedRequest_private *CeedRequest;
100 /// Handle for vectors over the field \ref CeedScalar
101 /// @ingroup CeedVector
102 typedef struct CeedVector_private *CeedVector;
103 /// Handle for object describing restriction to elements
104 /// @ingroup CeedElemRestriction
105 typedef struct CeedElemRestriction_private *CeedElemRestriction;
106 /// Handle for object describing discrete finite element evaluations
107 /// @ingroup CeedBasis
108 typedef struct CeedBasis_private *CeedBasis;
109 /// Handle for object describing functions evaluated independently at quadrature points
110 /// @ingroup CeedQFunction
111 typedef struct CeedQFunction_private *CeedQFunction;
112 /// Handle for object describing FE-type operators acting on vectors
113 ///
114 /// Given an element restriction \f$E\f$, basis evaluator \f$B\f$, and
115 ///   quadrature function\f$f\f$, a CeedOperator expresses operations of the form
116 ///   $$ E^T B^T f(B E u) $$
117 ///   acting on the vector \f$u\f$.
118 /// @ingroup CeedOperator
119 typedef struct CeedOperator_private *CeedOperator;
120 
121 CEED_EXTERN int CeedInit(const char *resource, Ceed *ceed);
122 CEED_EXTERN int CeedGetResource(Ceed ceed, const char **resource);
123 CEED_EXTERN int CeedDestroy(Ceed *ceed);
124 
125 CEED_EXTERN int CeedErrorImpl(Ceed, const char *, int, const char *, int,
126                               const char *, ...);
127 /// Raise an error on ceed object
128 ///
129 /// @param ceed Ceed library context or NULL
130 /// @param ecode Error code (int)
131 /// @param ... printf-style format string followed by arguments as needed
132 ///
133 /// @ingroup Ceed
134 /// @sa CeedSetErrorHandler()
135 #if defined(__clang__)
136 /// Use nonstandard ternary to convince the compiler/clang-tidy that this
137 /// function never returns zero.
138 #  define CeedError(ceed, ecode, ...)                                     \
139   (CeedErrorImpl((ceed), __FILE__, __LINE__, __func__, (ecode), __VA_ARGS__) ?: (ecode))
140 #else
141 #  define CeedError(ceed, ecode, ...)                                     \
142   CeedErrorImpl((ceed), __FILE__, __LINE__, __func__, (ecode), __VA_ARGS__) ?: (ecode)
143 #endif
144 /// Specify memory type
145 ///
146 /// Many Ceed interfaces take or return pointers to memory.  This enum is used to
147 /// specify where the memory being provided or requested must reside.
148 /// @ingroup Ceed
149 typedef enum {
150   /// Memory resides on the host
151   CEED_MEM_HOST,
152   /// Memory resides on a device (corresponding to \ref Ceed resource)
153   CEED_MEM_DEVICE,
154 } CeedMemType;
155 
156 CEED_EXTERN const char *const CeedMemTypes[];
157 
158 CEED_EXTERN int CeedGetPreferredMemType(Ceed ceed, CeedMemType *type);
159 
160 /// Conveys ownership status of arrays passed to Ceed interfaces.
161 /// @ingroup Ceed
162 typedef enum {
163   /// Implementation will copy the values and not store the passed pointer.
164   CEED_COPY_VALUES,
165   /// Implementation can use and modify the data provided by the user, but does
166   /// not take ownership.
167   CEED_USE_POINTER,
168   /// Implementation takes ownership of the pointer and will free using
169   /// CeedFree() when done using it.  The user should not assume that the
170   /// pointer remains valid after ownership has been transferred.  Note that
171   /// arrays allocated using C++ operator new or other allocators cannot
172   /// generally be freed using CeedFree().  CeedFree() is capable of freeing any
173   /// memory that can be freed using free(3).
174   CEED_OWN_POINTER,
175 } CeedCopyMode;
176 
177 /// Denotes type of vector norm to be computed
178 /// @ingroup CeedVector
179 typedef enum {
180   /// L_1 norm: sum_i |x_i|
181   CEED_NORM_1,
182   /// L_2 norm: sqrt(sum_i |x_i|^2)
183   CEED_NORM_2,
184   /// L_Infinity norm: max_i |x_i|
185   CEED_NORM_MAX,
186 } CeedNormType;
187 
188 CEED_EXTERN const char *const CeedCopyModes[];
189 
190 CEED_EXTERN int CeedVectorCreate(Ceed ceed, CeedInt len, CeedVector *vec);
191 CEED_EXTERN int CeedVectorSetArray(CeedVector vec, CeedMemType mtype,
192                                    CeedCopyMode cmode, CeedScalar *array);
193 CEED_EXTERN int CeedVectorSetValue(CeedVector vec, CeedScalar value);
194 CEED_EXTERN int CeedVectorSyncArray(CeedVector vec, CeedMemType mtype);
195 CEED_EXTERN int CeedVectorGetArray(CeedVector vec, CeedMemType mtype,
196                                    CeedScalar **array);
197 CEED_EXTERN int CeedVectorGetArrayRead(CeedVector vec, CeedMemType mtype,
198                                        const CeedScalar **array);
199 CEED_EXTERN int CeedVectorRestoreArray(CeedVector vec, CeedScalar **array);
200 CEED_EXTERN int CeedVectorRestoreArrayRead(CeedVector vec,
201     const CeedScalar **array);
202 CEED_EXTERN int CeedVectorNorm(CeedVector vec, CeedNormType type,
203                                CeedScalar *norm);
204 CEED_EXTERN int CeedVectorView(CeedVector vec, const char *fpfmt, FILE *stream);
205 CEED_EXTERN int CeedVectorGetLength(CeedVector vec, CeedInt *length);
206 CEED_EXTERN int CeedVectorDestroy(CeedVector *vec);
207 
208 CEED_EXTERN CeedRequest *const CEED_REQUEST_IMMEDIATE;
209 CEED_EXTERN CeedRequest *const CEED_REQUEST_ORDERED;
210 CEED_EXTERN int CeedRequestWait(CeedRequest *req);
211 
212 /// Argument for CeedOperatorSetField that vector is collocated with
213 /// quadrature points, used with QFunction eval mode CEED_EVAL_NONE
214 /// or CEED_EVAL_INTERP only, not with CEED_EVAL_GRAD, CEED_EVAL_DIV,
215 /// or CEED_EVAL_CURL
216 /// @ingroup CeedBasis
217 CEED_EXTERN CeedBasis CEED_BASIS_COLLOCATED;
218 
219 /// Argument for CeedOperatorSetField to use active input or output
220 /// @ingroup CeedVector
221 CEED_EXTERN CeedVector CEED_VECTOR_ACTIVE;
222 
223 /// Argument for CeedOperatorSetField to use no vector, used with
224 /// qfunction input with eval mode CEED_EVAL_WEIGHTS
225 /// @ingroup CeedVector
226 CEED_EXTERN CeedVector CEED_VECTOR_NONE;
227 
228 /// Argument for CeedOperatorCreate that QFunction is not created by user.
229 /// Only used for QFunctions dqf and dqfT. If implemented, a backend may
230 /// attempt to provide the action of these QFunctions.
231 /// @ingroup CeedQFunction
232 CEED_EXTERN CeedQFunction CEED_QFUNCTION_NONE;
233 
234 /// Denotes whether a linear transformation or its transpose should be applied
235 /// @ingroup CeedBasis
236 typedef enum {
237   /// Apply the linear transformation
238   CEED_NOTRANSPOSE,
239   /// Apply the transpose
240   CEED_TRANSPOSE
241 } CeedTransposeMode;
242 
243 CEED_EXTERN const char *const CeedTransposeModes[];
244 
245 /// Denotes whether a L-vector is ordered [component, node] or [node, component]
246 ///   with the right-most index being contiguous in memory
247 /// @ingroup CeedElemRestriction
248 typedef enum {
249   /// L-vector data is not interlaced, ordered [component, node]
250   CEED_NONINTERLACED,
251   /// L-vector data is interlaced, ordered [node, component]
252   CEED_INTERLACED
253 } CeedInterlaceMode;
254 
255 CEED_EXTERN const char *const CeedInterlaceModes[];
256 
257 CEED_EXTERN int CeedElemRestrictionCreate(Ceed ceed, CeedInterlaceMode imode,
258     CeedInt nelem, CeedInt elemsize, CeedInt nnodes, CeedInt ncomp,
259     CeedMemType mtype, CeedCopyMode cmode, const CeedInt *indices,
260     CeedElemRestriction *rstr);
261 CEED_EXTERN int CeedElemRestrictionCreateIdentity(Ceed ceed,
262     CeedInterlaceMode imode,CeedInt nelem, CeedInt elemsize, CeedInt nnodes,
263     CeedInt ncomp, CeedElemRestriction *rstr);
264 CEED_EXTERN int CeedElemRestrictionCreateBlocked(Ceed ceed,
265     CeedInterlaceMode imode,CeedInt nelem, CeedInt elemsize, CeedInt blksize,
266     CeedInt nnodes, CeedInt ncomp, CeedMemType mtype, CeedCopyMode cmode,
267     const CeedInt *indices, CeedElemRestriction *rstr);
268 CEED_EXTERN int CeedElemRestrictionCreateVector(CeedElemRestriction rstr,
269     CeedVector *lvec, CeedVector *evec);
270 CEED_EXTERN int CeedElemRestrictionApply(CeedElemRestriction rstr,
271     CeedTransposeMode tmode, CeedVector u, CeedVector ru, CeedRequest *request);
272 CEED_EXTERN int CeedElemRestrictionApplyBlock(CeedElemRestriction rstr,
273     CeedInt block, CeedTransposeMode tmode, CeedVector u, CeedVector ru,
274     CeedRequest *request);
275 CEED_EXTERN int CeedElemRestrictionGetIMode(CeedElemRestriction rstr,
276     CeedInterlaceMode *Imode);
277 CEED_EXTERN int CeedElemRestrictionGetNumElements(CeedElemRestriction rstr,
278     CeedInt *numelem);
279 CEED_EXTERN int CeedElemRestrictionGetElementSize(CeedElemRestriction rstr,
280     CeedInt *elemsize);
281 CEED_EXTERN int CeedElemRestrictionGetNumNodes(CeedElemRestriction rstr,
282     CeedInt *numnodes);
283 CEED_EXTERN int CeedElemRestrictionGetNumComponents(CeedElemRestriction rstr,
284     CeedInt *numcomp);
285 CEED_EXTERN int CeedElemRestrictionGetNumBlocks(CeedElemRestriction rstr,
286     CeedInt *numblk);
287 CEED_EXTERN int CeedElemRestrictionGetBlockSize(CeedElemRestriction rstr,
288     CeedInt *blksize);
289 CEED_EXTERN int CeedElemRestrictionGetMultiplicity(CeedElemRestriction rstr,
290     CeedVector mult);
291 CEED_EXTERN int CeedElemRestrictionView(CeedElemRestriction rstr, FILE *stream);
292 CEED_EXTERN int CeedElemRestrictionDestroy(CeedElemRestriction *rstr);
293 
294 /// The formalism here is that we have the structure
295 ///   \int_\Omega v^T f_0(u, \nabla u, qdata) + (\nabla v)^T f_1(u, \nabla u, qdata)
296 /// where gradients are with respect to the reference element.
297 
298 /// Basis evaluation mode
299 ///
300 /// Modes can be bitwise ORed when passing to most functions.
301 /// @ingroup CeedBasis
302 typedef enum {
303   /// Perform no evaluation (either because there is no data or it is already at
304   /// quadrature points)
305   CEED_EVAL_NONE   = 0,
306   /// Interpolate from nodes to quadrature points
307   CEED_EVAL_INTERP = 1,
308   /// Evaluate gradients at quadrature points from input in a nodal basis
309   CEED_EVAL_GRAD   = 2,
310   /// Evaluate divergence at quadrature points from input in a nodal basis
311   CEED_EVAL_DIV    = 4,
312   /// Evaluate curl at quadrature points from input in a nodal basis
313   CEED_EVAL_CURL   = 8,
314   /// Using no input, evaluate quadrature weights on the reference element
315   CEED_EVAL_WEIGHT = 16,
316 } CeedEvalMode;
317 
318 CEED_EXTERN const char *const CeedEvalModes[];
319 
320 /// Type of quadrature; also used for location of nodes
321 /// @ingroup CeedBasis
322 typedef enum {
323   /// Gauss-Legendre quadrature
324   CEED_GAUSS = 0,
325   /// Gauss-Legendre-Lobatto quadrature
326   CEED_GAUSS_LOBATTO = 1,
327 } CeedQuadMode;
328 
329 CEED_EXTERN const char *const CeedQuadModes[];
330 
331 /// Type of basis shape to create non-tensor H1 element basis
332 ///
333 /// Dimension can be extracted with bitwise AND
334 /// (CeedElemTopology & 2**(dim + 2)) == TRUE
335 /// @ingroup CeedBasis
336 typedef enum {
337   /// Line
338   CEED_LINE = 1 << 16 | 0,
339   /// Triangle - 2D shape
340   CEED_TRIANGLE = 2 << 16 | 1,
341   /// Quadralateral - 2D shape
342   CEED_QUAD = 2 << 16 | 2,
343   /// Tetrahedron - 3D shape
344   CEED_TET = 3 << 16 | 3,
345   /// Pyramid - 3D shape
346   CEED_PYRAMID = 3 << 16 | 4,
347   /// Prism - 3D shape
348   CEED_PRISM = 3 << 16 | 5,
349   /// Hexehedron - 3D shape
350   CEED_HEX = 3 << 16 | 6,
351 } CeedElemTopology;
352 
353 CEED_EXTERN const char *const CeedElemTopologies[];
354 
355 CEED_EXTERN int CeedBasisCreateTensorH1Lagrange(Ceed ceed, CeedInt dim,
356     CeedInt ncomp, CeedInt P, CeedInt Q, CeedQuadMode qmode, CeedBasis *basis);
357 CEED_EXTERN int CeedBasisCreateTensorH1(Ceed ceed, CeedInt dim, CeedInt ncomp,
358                                         CeedInt P1d, CeedInt Q1d,
359                                         const CeedScalar *interp1d,
360                                         const CeedScalar *grad1d,
361                                         const CeedScalar *qref1d,
362                                         const CeedScalar *qweight1d,
363                                         CeedBasis *basis);
364 CEED_EXTERN int CeedBasisCreateH1(Ceed ceed, CeedElemTopology topo,
365                                   CeedInt ncomp,
366                                   CeedInt nnodes, CeedInt nqpts,
367                                   const CeedScalar *interp,
368                                   const CeedScalar *grad,
369                                   const CeedScalar *qref,
370                                   const CeedScalar *qweight, CeedBasis *basis);
371 CEED_EXTERN int CeedBasisView(CeedBasis basis, FILE *stream);
372 CEED_EXTERN int CeedBasisGetNumNodes(CeedBasis basis, CeedInt *P);
373 CEED_EXTERN int CeedBasisGetNumQuadraturePoints(CeedBasis basis, CeedInt *Q);
374 CEED_EXTERN int CeedBasisApply(CeedBasis basis, CeedInt nelem,
375                                CeedTransposeMode tmode,
376                                CeedEvalMode emode, CeedVector u, CeedVector v);
377 CEED_EXTERN int CeedBasisDestroy(CeedBasis *basis);
378 
379 CEED_EXTERN int CeedGaussQuadrature(CeedInt Q, CeedScalar *qref1d,
380                                     CeedScalar *qweight1d);
381 CEED_EXTERN int CeedLobattoQuadrature(CeedInt Q, CeedScalar *qref1d,
382                                       CeedScalar *qweight1d);
383 CEED_EXTERN int CeedQRFactorization(Ceed ceed, CeedScalar *mat, CeedScalar *tau,
384                                     CeedInt m, CeedInt n);
385 CEED_EXTERN int CeedSymmetricSchurDecomposition(Ceed ceed, CeedScalar *mat,
386     CeedScalar *lambda, CeedInt n);
387 CEED_EXTERN int CeedSimultaneousDiagonalization(Ceed ceed, CeedScalar *matA,
388     CeedScalar *matB, CeedScalar *x, CeedScalar *lambda, CeedInt n);
389 
390 /** Handle for the object describing the user CeedQFunction
391 
392  @param ctx user-defined context set using CeedQFunctionSetContext() or NULL
393 
394  @param Q   number of quadrature points at which to evaluate
395 
396  @param in  array of pointers to each input argument in the order provided
397               by the user in CeedQFunctionAddInput().  Each array has shape
398               `[dim, ncomp, Q]` where `dim` is the geometric dimension for
399               \ref CEED_EVAL_GRAD (`dim=1` for \ref CEED_EVAL_INTERP) and
400               `ncomp` is the number of field components (`ncomp=1` for
401               scalar fields).  This results in indexing the `i`th input at
402               quadrature point `j` as `in[i][(d*ncomp + c)*Q + j]`.
403 
404  @param out array of pointers to each output array in the order provided
405               using CeedQFunctionAddOutput().  The shapes are as above for
406               \a in.
407 
408  @return An error code: 0 - success, otherwise - failure
409 
410  @ingroup CeedQFunction
411 **/
412 typedef int (*CeedQFunctionUser)(void *ctx, const CeedInt Q,
413                                  const CeedScalar *const *in,
414                                  CeedScalar *const *out);
415 
416 CEED_EXTERN int CeedQFunctionCreateInterior(Ceed ceed, CeedInt vlength,
417     CeedQFunctionUser f, const char *source, CeedQFunction *qf);
418 CEED_EXTERN int CeedQFunctionCreateInteriorByName(Ceed ceed, const char *name,
419     CeedQFunction *qf);
420 CEED_EXTERN int CeedQFunctionCreateIdentity(Ceed ceed, CeedInt size,
421     CeedEvalMode inmode, CeedEvalMode outmode, CeedQFunction *qf);
422 CEED_EXTERN int CeedQFunctionAddInput(CeedQFunction qf, const char *fieldname,
423                                       CeedInt size, CeedEvalMode emode);
424 CEED_EXTERN int CeedQFunctionAddOutput(CeedQFunction qf, const char *fieldname,
425                                        CeedInt size, CeedEvalMode emode);
426 CEED_EXTERN int CeedQFunctionSetContext(CeedQFunction qf, void *ctx,
427                                         size_t ctxsize);
428 CEED_EXTERN int CeedQFunctionView(CeedQFunction qf, FILE *stream);
429 CEED_EXTERN int CeedQFunctionApply(CeedQFunction qf, CeedInt Q,
430                                    CeedVector *u, CeedVector *v);
431 CEED_EXTERN int CeedQFunctionDestroy(CeedQFunction *qf);
432 
433 CEED_EXTERN int CeedOperatorCreate(Ceed ceed, CeedQFunction qf,
434                                    CeedQFunction dqf, CeedQFunction dqfT,
435                                    CeedOperator *op);
436 CEED_EXTERN int CeedCompositeOperatorCreate(Ceed ceed, CeedOperator *op);
437 CEED_EXTERN int CeedOperatorSetField(CeedOperator op, const char *fieldname,
438                                      CeedElemRestriction r, CeedBasis b,
439                                      CeedVector v);
440 CEED_EXTERN int CeedCompositeOperatorAddSub(CeedOperator compositeop,
441     CeedOperator subop);
442 CEED_EXTERN int CeedOperatorAssembleLinearQFunction(CeedOperator op,
443     CeedVector *assembled, CeedElemRestriction *rstr, CeedRequest *request);
444 CEED_EXTERN int CeedOperatorAssembleLinearDiagonal(CeedOperator op,
445     CeedVector *assembled, CeedRequest *request);
446 CEED_EXTERN int CeedOperatorView(CeedOperator op, FILE *stream);
447 CEED_EXTERN int CeedOperatorCreateFDMElementInverse(CeedOperator op,
448     CeedOperator *fdminv, CeedRequest *request);
449 CEED_EXTERN int CeedOperatorApply(CeedOperator op, CeedVector in,
450                                   CeedVector out, CeedRequest *request);
451 CEED_EXTERN int CeedOperatorApplyAdd(CeedOperator op, CeedVector in,
452                                      CeedVector out, CeedRequest *request);
453 CEED_EXTERN int CeedOperatorDestroy(CeedOperator *op);
454 
455 /**
456   @brief Return integer power
457 
458   @param[in] base   The base to exponentiate
459   @param[in] power  The power to raise the base to
460 
461   @return base^power
462 
463   @ref Utility
464 **/
465 static inline CeedInt CeedIntPow(CeedInt base, CeedInt power) {
466   CeedInt result = 1;
467   while (power) {
468     if (power & 1) result *= base;
469     power >>= 1;
470     base *= base;
471   }
472   return result;
473 }
474 
475 /**
476   @brief Return minimum of two integers
477 
478   @param[in] a  The first integer to compare
479   @param[in] b  The second integer to compare
480 
481   @return The minimum of the two integers
482 
483   @ref Utility
484 **/
485 static inline CeedInt CeedIntMin(CeedInt a, CeedInt b) { return a < b ? a : b; }
486 
487 #endif
488