xref: /libCEED/interface/ceed-elemrestriction.c (revision 7509a596beda7c1d002d2274a17375b09541fdb6)
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 #include <ceed-impl.h>
18 #include <ceed-backend.h>
19 
20 /// @file
21 /// Implementation of public CeedElemRestriction interfaces
22 ///
23 /// @addtogroup CeedElemRestriction
24 /// @{
25 
26 /**
27   @brief Create a CeedElemRestriction
28 
29   @param ceed       A Ceed object where the CeedElemRestriction will be created
30   @param imode      Ordering of the ncomp components, i.e. it specifies
31                       the ordering of the components of the L-vector used
32                       by this CeedElemRestriction. CEED_NONINTERLACED indicates
33                       the component is the outermost index and CEED_INTERLACED
34                       indicates the component is the innermost index in
35                       ordering of the L-vector.
36   @param nelem      Number of elements described in the @a indices array
37   @param elemsize   Size (number of "nodes") per element
38   @param nnodes     The number of nodes in the L-vector. The input CeedVector
39                       to which the restriction will be applied is of size
40                       @a nnodes * @a ncomp. This size may include data
41                       used by other CeedElemRestriction objects describing
42                       different types of elements.
43   @param ncomp      Number of field components per interpolation node
44                       (1 for scalar fields)
45   @param mtype      Memory type of the @a indices array, see CeedMemType
46   @param cmode      Copy mode for the @a indices array, see CeedCopyMode
47   @param indices    Array of shape [@a nelem, @a elemsize]. Row i holds the
48                       ordered list of the indices (into the input CeedVector)
49                       for the unknowns corresponding to element i, where
50                       0 <= i < @a nelem. All indices must be in the range
51                       [0, @a nnodes - 1].
52   @param[out] rstr  Address of the variable where the newly created
53                       CeedElemRestriction will be stored
54 
55   @return An error code: 0 - success, otherwise - failure
56 
57   @ref Basic
58 **/
59 int CeedElemRestrictionCreate(Ceed ceed, CeedInterlaceMode imode,
60                               CeedInt nelem, CeedInt elemsize, CeedInt nnodes,
61                               CeedInt ncomp, CeedMemType mtype,
62                               CeedCopyMode cmode, const CeedInt *indices,
63                               CeedElemRestriction *rstr) {
64   int ierr;
65 
66   if (!ceed->ElemRestrictionCreate) {
67     Ceed delegate;
68     ierr = CeedGetObjectDelegate(ceed, &delegate, "ElemRestriction");
69     CeedChk(ierr);
70 
71     if (!delegate)
72       // LCOV_EXCL_START
73       return CeedError(ceed, 1, "Backend does not support ElemRestrictionCreate");
74     // LCOV_EXCL_STOP
75 
76     ierr = CeedElemRestrictionCreate(delegate, imode, nelem, elemsize,
77                                      nnodes, ncomp, mtype, cmode,
78                                      indices, rstr); CeedChk(ierr);
79     return 0;
80   }
81 
82   ierr = CeedCalloc(1, rstr); CeedChk(ierr);
83   (*rstr)->ceed = ceed;
84   ceed->refcount++;
85   (*rstr)->refcount = 1;
86   (*rstr)->imode = imode;
87   (*rstr)->nelem = nelem;
88   (*rstr)->elemsize = elemsize;
89   (*rstr)->nnodes = nnodes;
90   (*rstr)->ncomp = ncomp;
91   (*rstr)->nblk = nelem;
92   (*rstr)->blksize = 1;
93   ierr = ceed->ElemRestrictionCreate(mtype, cmode, indices, *rstr); CeedChk(ierr);
94   return 0;
95 }
96 
97 /**
98   @brief Create a strided CeedElemRestriction
99 
100   @param ceed       A Ceed object where the CeedElemRestriction will be created
101   @param nelem      Number of elements described by the restriction
102   @param elemsize   Size (number of "nodes") per element
103   @param nnodes     The number of nodes in the L-vector. The input CeedVector
104                       to which the restriction will be applied is of size
105                       @a nnodes * @a ncomp. This size may include data
106                       used by other CeedElemRestriction objects describing
107                       different types of elements.
108   @param ncomp      Number of field components per interpolation node
109                       (1 for scalar fields)
110   @param strides    Array for strides between [nodes, components, elements].
111                       The data for node i, component j, element k in the
112                       L-vector is given by
113                         i*strides[0] + j*strides[1] + k*strides[2]
114   @param rstr       Address of the variable where the newly created
115                       CeedElemRestriction will be stored
116 
117   @return An error code: 0 - success, otherwise - failure
118 
119   @ref Basic
120 **/
121 int CeedElemRestrictionCreateStrided(Ceed ceed, CeedInt nelem, CeedInt elemsize,
122                                      CeedInt nnodes, CeedInt ncomp,
123                                      CeedInt strides[3],
124                                      CeedElemRestriction *rstr) {
125   int ierr;
126 
127   if (!ceed->ElemRestrictionCreate) {
128     Ceed delegate;
129     ierr = CeedGetObjectDelegate(ceed, &delegate, "ElemRestriction");
130     CeedChk(ierr);
131 
132     if (!delegate)
133       // LCOV_EXCL_START
134       return CeedError(ceed, 1, "Backend does not support ElemRestrictionCreate");
135     // LCOV_EXCL_STOP
136 
137     ierr = CeedElemRestrictionCreateStrided(delegate, nelem, elemsize, nnodes,
138                                             ncomp, strides, rstr); CeedChk(ierr);
139     return 0;
140   }
141 
142   ierr = CeedCalloc(1, rstr); CeedChk(ierr);
143   (*rstr)->ceed = ceed;
144   ceed->refcount++;
145   (*rstr)->refcount = 1;
146   (*rstr)->nelem = nelem;
147   (*rstr)->elemsize = elemsize;
148   (*rstr)->nnodes = nnodes;
149   (*rstr)->ncomp = ncomp;
150   (*rstr)->nblk = nelem;
151   (*rstr)->blksize = 1;
152   ierr = CeedMalloc(3, &(*rstr)->strides); CeedChk(ierr);
153   for (int i = 0; i<3; i++)
154     (*rstr)->strides[i] = strides[i];
155   ierr = ceed->ElemRestrictionCreate(CEED_MEM_HOST, CEED_OWN_POINTER, NULL,
156                                      *rstr);
157   CeedChk(ierr);
158   return 0;
159 }
160 
161 /**
162   @brief Permute and pad indices for a blocked restriction
163 
164   @param indices    Array of shape [@a nelem, @a elemsize]. Row i holds the
165                       ordered list of the indices (into the input CeedVector)
166                       for the unknowns corresponding to element i, where
167                       0 <= i < @a nelem. All indices must be in the range
168                       [0, @a nnodes).
169   @param blkindices Array of permuted and padded indices of
170                       shape [@a nblk, @a elemsize, @a blksize].
171   @param nblk       Number of blocks
172   @param nelem      Number of elements
173   @param blksize    Number of elements in a block
174   @param elemsize   Size of each element
175 
176   @return An error code: 0 - success, otherwise - failure
177 
178   @ref Utility
179 **/
180 int CeedPermutePadIndices(const CeedInt *indices, CeedInt *blkindices,
181                           CeedInt nblk, CeedInt nelem, CeedInt blksize,
182                           CeedInt elemsize) {
183   for (CeedInt e = 0; e < nblk*blksize; e+=blksize)
184     for (int j = 0; j < blksize; j++)
185       for (int k = 0; k < elemsize; k++)
186         blkindices[e*elemsize + k*blksize + j]
187           = indices[CeedIntMin(e+j,nelem-1)*elemsize + k];
188   return 0;
189 }
190 
191 /**
192   @brief Create a blocked CeedElemRestriction, typically only called by backends
193 
194   @param ceed       A Ceed object where the CeedElemRestriction will be created.
195   @param imode      Ordering of the ncomp components, i.e. it specifies
196                       the ordering of the components of the L-vector used
197                       by this CeedElemRestriction. CEED_NONINTERLACED indicates
198                       the component is the outermost index and CEED_INTERLACED
199                       indicates the component is the innermost index in
200                       ordering of the L-vector.
201   @param nelem      Number of elements described in the @a indices array.
202   @param elemsize   Size (number of unknowns) per element
203   @param blksize    Number of elements in a block
204   @param nnodes     The number of nodes in the L-vector. The input CeedVector
205                       to which the restriction will be applied is of size
206                       @a nnodes * @a ncomp. This size may include data
207                       used by other CeedElemRestriction objects describing
208                       different types of elements.
209   @param ncomp      Number of field components per interpolation node
210                       (1 for scalar fields)
211   @param mtype      Memory type of the @a indices array, see CeedMemType
212   @param cmode      Copy mode for the @a indices array, see CeedCopyMode
213   @param indices    Array of shape [@a nelem, @a elemsize]. Row i holds the
214                       ordered list of the indices (into the input CeedVector)
215                       for the unknowns corresponding to element i, where
216                       0 <= i < @a nelem. All indices must be in the range
217                       [0, @a nnodes). The backend will permute and pad this
218                       array to the desired ordering for the blocksize, which is
219                       typically given by the backend. The default reordering is
220                       to interlace elements.
221   @param rstr       Address of the variable where the newly created
222                       CeedElemRestriction will be stored
223 
224   @return An error code: 0 - success, otherwise - failure
225 
226   @ref Advanced
227  **/
228 int CeedElemRestrictionCreateBlocked(Ceed ceed,  CeedInterlaceMode imode,
229                                      CeedInt nelem, CeedInt elemsize,
230                                      CeedInt blksize, CeedInt nnodes,
231                                      CeedInt ncomp, CeedMemType mtype,
232                                      CeedCopyMode cmode, const CeedInt *indices,
233                                      CeedElemRestriction *rstr) {
234   int ierr;
235   CeedInt *blkindices;
236   CeedInt nblk = (nelem / blksize) + !!(nelem % blksize);
237 
238   if (!ceed->ElemRestrictionCreateBlocked) {
239     Ceed delegate;
240     ierr = CeedGetObjectDelegate(ceed, &delegate, "ElemRestriction");
241     CeedChk(ierr);
242 
243     if (!delegate)
244       // LCOV_EXCL_START
245       return CeedError(ceed, 1, "Backend does not support "
246                        "ElemRestrictionCreateBlocked");
247     // LCOV_EXCL_STOP
248 
249     ierr = CeedElemRestrictionCreateBlocked(delegate, imode, nelem, elemsize,
250                                             blksize, nnodes, ncomp, mtype, cmode,
251                                             indices, rstr); CeedChk(ierr);
252     return 0;
253   }
254 
255   ierr = CeedCalloc(1, rstr); CeedChk(ierr);
256 
257   if (indices) {
258     ierr = CeedCalloc(nblk*blksize*elemsize, &blkindices); CeedChk(ierr);
259     ierr = CeedPermutePadIndices(indices, blkindices, nblk, nelem, blksize,
260                                  elemsize);
261     CeedChk(ierr);
262   } else {
263     blkindices = NULL;
264   }
265 
266   (*rstr)->ceed = ceed;
267   ceed->refcount++;
268   (*rstr)->refcount = 1;
269   (*rstr)->imode = imode;
270   (*rstr)->nelem = nelem;
271   (*rstr)->elemsize = elemsize;
272   (*rstr)->nnodes = nnodes;
273   (*rstr)->ncomp = ncomp;
274   (*rstr)->nblk = nblk;
275   (*rstr)->blksize = blksize;
276   ierr = ceed->ElemRestrictionCreateBlocked(CEED_MEM_HOST, CEED_OWN_POINTER,
277          (const CeedInt *) blkindices, *rstr); CeedChk(ierr);
278 
279   if (cmode == CEED_OWN_POINTER) {
280     ierr = CeedFree(&indices); CeedChk(ierr);
281   }
282 
283   return 0;
284 }
285 
286 /**
287   @brief Create a blocked strided CeedElemRestriction
288 
289   @param ceed       A Ceed object where the CeedElemRestriction will be created
290   @param nelem      Number of elements described by the restriction
291   @param elemsize   Size (number of "nodes") per element
292   @param blksize    Number of elements in a block
293   @param nnodes     The number of nodes in the L-vector. The input CeedVector
294                       to which the restriction will be applied is of size
295                       @a nnodes * @a ncomp. This size may include data
296                       used by other CeedElemRestriction objects describing
297                       different types of elements.
298   @param ncomp      Number of field components per interpolation node
299                       (1 for scalar fields)
300   @param strides    Array for strides between [nodes, components, elements].
301                       The data for node i, component j, element k in the
302                       L-vector is given by
303                         i*strides[0] + j*strides[1] + k*strides[2]
304   @param rstr       Address of the variable where the newly created
305                       CeedElemRestriction will be stored
306 
307   @return An error code: 0 - success, otherwise - failure
308 
309   @ref Basic
310 **/
311 int CeedElemRestrictionCreateBlockedStrided(Ceed ceed, CeedInt nelem,
312     CeedInt elemsize, CeedInt blksize,
313     CeedInt nnodes, CeedInt ncomp,
314     CeedInt strides[3],
315     CeedElemRestriction *rstr) {
316   int ierr;
317   CeedInt nblk = (nelem / blksize) + !!(nelem % blksize);
318 
319   if (!ceed->ElemRestrictionCreateBlocked) {
320     Ceed delegate;
321     ierr = CeedGetObjectDelegate(ceed, &delegate, "ElemRestriction");
322     CeedChk(ierr);
323 
324     if (!delegate)
325       // LCOV_EXCL_START
326       return CeedError(ceed, 1, "Backend does not support "
327                        "ElemRestrictionCreateBlocked");
328     // LCOV_EXCL_STOP
329 
330     ierr = CeedElemRestrictionCreateBlockedStrided(delegate, nelem, elemsize,
331            blksize, nnodes, ncomp,
332            strides, rstr);
333     CeedChk(ierr);
334     return 0;
335   }
336 
337   ierr = CeedCalloc(1, rstr); CeedChk(ierr);
338 
339   (*rstr)->ceed = ceed;
340   ceed->refcount++;
341   (*rstr)->refcount = 1;
342   (*rstr)->nelem = nelem;
343   (*rstr)->elemsize = elemsize;
344   (*rstr)->nnodes = nnodes;
345   (*rstr)->ncomp = ncomp;
346   (*rstr)->nblk = nblk;
347   (*rstr)->blksize = blksize;
348   ierr = CeedMalloc(3, &(*rstr)->strides); CeedChk(ierr);
349   for (int i = 0; i<3; i++)
350     (*rstr)->strides[i] = strides[i];
351   ierr = ceed->ElemRestrictionCreateBlocked(CEED_MEM_HOST, CEED_OWN_POINTER,
352          NULL, *rstr); CeedChk(ierr);
353 
354   return 0;
355 }
356 
357 /**
358   @brief Create CeedVectors associated with a CeedElemRestriction
359 
360   @param rstr  CeedElemRestriction
361   @param lvec  The address of the L-vector to be created, or NULL
362   @param evec  The address of the E-vector to be created, or NULL
363 
364   @return An error code: 0 - success, otherwise - failure
365 
366   @ref Advanced
367 **/
368 int CeedElemRestrictionCreateVector(CeedElemRestriction rstr, CeedVector *lvec,
369                                     CeedVector *evec) {
370   int ierr;
371   CeedInt n, m;
372   m = rstr->nnodes * rstr->ncomp;
373   n = rstr->nblk * rstr->blksize * rstr->elemsize * rstr->ncomp;
374   if (lvec) {
375     ierr = CeedVectorCreate(rstr->ceed, m, lvec); CeedChk(ierr);
376   }
377   if (evec) {
378     ierr = CeedVectorCreate(rstr->ceed, n, evec); CeedChk(ierr);
379   }
380   return 0;
381 }
382 
383 /**
384   @brief Restrict an L-vector to an E-vector or apply its transpose
385 
386   @param rstr    CeedElemRestriction
387   @param tmode   Apply restriction or transpose
388   @param u       Input vector (of shape [@a nnodes, @a ncomp] when
389                    tmode=CEED_NOTRANSPOSE, imode=CEED_INTERLACED)
390   @param ru      Output vector (of shape [@a nelem * @a elemsize] when
391                    tmode=CEED_NOTRANSPOSE). Ordering of the e-vector is decided
392                    by the backend.
393   @param request Request or CEED_REQUEST_IMMEDIATE
394 
395   @return An error code: 0 - success, otherwise - failure
396 
397   @ref Advanced
398 **/
399 int CeedElemRestrictionApply(CeedElemRestriction rstr, CeedTransposeMode tmode,
400                              CeedVector u, CeedVector ru,
401                              CeedRequest *request) {
402   CeedInt m,n;
403   int ierr;
404 
405   if (tmode == CEED_NOTRANSPOSE) {
406     m = rstr->nblk * rstr->blksize * rstr->elemsize * rstr->ncomp;
407     n = rstr->nnodes * rstr->ncomp;
408   } else {
409     m = rstr->nnodes * rstr->ncomp;
410     n = rstr->nblk * rstr->blksize * rstr->elemsize * rstr->ncomp;
411   }
412   if (n != u->length)
413     // LCOV_EXCL_START
414     return CeedError(rstr->ceed, 2, "Input vector size %d not compatible with "
415                      "element restriction (%d, %d)", u->length, m, n);
416   // LCOV_EXCL_STOP
417   if (m != ru->length)
418     // LCOV_EXCL_START
419     return CeedError(rstr->ceed, 2, "Output vector size %d not compatible with "
420                      "element restriction (%d, %d)", ru->length, m, n);
421   // LCOV_EXCL_STOP
422   ierr = rstr->Apply(rstr, tmode, u, ru, request); CeedChk(ierr);
423 
424   return 0;
425 }
426 
427 /**
428   @brief Restrict an L-vector to a block of an E-vector or apply its transpose
429 
430   @param rstr    CeedElemRestriction
431   @param block   Block number to restrict to/from, i.e. block=0 will handle
432                    elements [0 : blksize] and block=3 will handle elements
433                    [3*blksize : 4*blksize]
434   @param tmode   Apply restriction or transpose
435   @param u       Input vector (of shape [@a nnodes, @a ncomp] when
436                    tmode=CEED_NOTRANSPOSE, imode=CEED_INTERLACED)
437   @param ru      Output vector (of shape [@a blksize * @a elemsize] when
438                    tmode=CEED_NOTRANSPOSE). Ordering of the e-vector is decided
439                    by the backend.
440   @param request Request or CEED_REQUEST_IMMEDIATE
441 
442   @return An error code: 0 - success, otherwise - failure
443 
444   @ref Advanced
445 **/
446 int CeedElemRestrictionApplyBlock(CeedElemRestriction rstr, CeedInt block,
447                                   CeedTransposeMode tmode, CeedVector u,
448                                   CeedVector ru, CeedRequest *request) {
449   CeedInt m,n;
450   int ierr;
451 
452   if (tmode == CEED_NOTRANSPOSE) {
453     m = rstr->blksize * rstr->elemsize * rstr->ncomp;
454     n = rstr->nnodes * rstr->ncomp;
455   } else {
456     m = rstr->nnodes * rstr->ncomp;
457     n = rstr->blksize * rstr->elemsize * rstr->ncomp;
458   }
459   if (n != u->length)
460     // LCOV_EXCL_START
461     return CeedError(rstr->ceed, 2, "Input vector size %d not compatible with "
462                      "element restriction (%d, %d)", u->length, m, n);
463   // LCOV_EXCL_STOP
464   if (m != ru->length)
465     // LCOV_EXCL_START
466     return CeedError(rstr->ceed, 2, "Output vector size %d not compatible with "
467                      "element restriction (%d, %d)", ru->length, m, n);
468   // LCOV_EXCL_STOP
469   if (rstr->blksize*block > rstr->nelem)
470     // LCOV_EXCL_START
471     return CeedError(rstr->ceed, 2, "Cannot retrieve block %d, element %d > "
472                      "total elements %d", block, rstr->blksize*block,
473                      rstr->nelem);
474   // LCOV_EXCL_STOP
475   ierr = rstr->ApplyBlock(rstr, block, tmode, u, ru, request);
476   CeedChk(ierr);
477 
478   return 0;
479 }
480 
481 /**
482   @brief Get the multiplicity of nodes in a CeedElemRestriction
483 
484   @param rstr             CeedElemRestriction
485   @param[out] mult        Vector to store multiplicity (of size nnodes*ncomp)
486 
487   @return An error code: 0 - success, otherwise - failure
488 
489   @ref Advanced
490 **/
491 int CeedElemRestrictionGetMultiplicity(CeedElemRestriction rstr,
492                                        CeedVector mult) {
493   int ierr;
494   CeedVector evec;
495 
496   // Create and set evec
497   ierr = CeedElemRestrictionCreateVector(rstr, NULL, &evec); CeedChk(ierr);
498   ierr = CeedVectorSetValue(evec, 1.0); CeedChk(ierr);
499   ierr = CeedVectorSetValue(mult, 0.0); CeedChk(ierr);
500 
501   // Apply to get multiplicity
502   ierr = CeedElemRestrictionApply(rstr, CEED_TRANSPOSE, evec, mult,
503                                   CEED_REQUEST_IMMEDIATE); CeedChk(ierr);
504 
505   // Cleanup
506   ierr = CeedVectorDestroy(&evec); CeedChk(ierr);
507 
508   return 0;
509 }
510 
511 /**
512   @brief Get the Ceed associated with a CeedElemRestriction
513 
514   @param rstr             CeedElemRestriction
515   @param[out] ceed        Variable to store Ceed
516 
517   @return An error code: 0 - success, otherwise - failure
518 
519   @ref Advanced
520 **/
521 int CeedElemRestrictionGetCeed(CeedElemRestriction rstr, Ceed *ceed) {
522   *ceed = rstr->ceed;
523   return 0;
524 }
525 
526 /**
527   @brief Get the L-vector interlaced mode of a CeedElemRestriction
528 
529   @param rstr             CeedElemRestriction
530   @param[out] imode       Variable to store imode
531 
532   @return An error code: 0 - success, otherwise - failure
533 
534   @ref Advanced
535 **/
536 int CeedElemRestrictionGetIMode(CeedElemRestriction rstr,
537                                 CeedInterlaceMode *imode) {
538   if (rstr->strides)
539     // LCOV_EXCL_START
540     return CeedError(rstr->ceed, 1, "Strided ElemRestriction has no interlace "
541                      "mode");
542   // LCOV_EXCL_STOP
543 
544   *imode = rstr->imode;
545   return 0;
546 }
547 
548 /**
549   @brief Get the total number of elements in the range of a CeedElemRestriction
550 
551   @param rstr             CeedElemRestriction
552   @param[out] numelem     Variable to store number of elements
553 
554   @return An error code: 0 - success, otherwise - failure
555 
556   @ref Advanced
557 **/
558 int CeedElemRestrictionGetNumElements(CeedElemRestriction rstr,
559                                       CeedInt *numelem) {
560   *numelem = rstr->nelem;
561   return 0;
562 }
563 
564 /**
565   @brief Get the size of elements in the CeedElemRestriction
566 
567   @param rstr             CeedElemRestriction
568   @param[out] elemsize    Variable to store size of elements
569 
570   @return An error code: 0 - success, otherwise - failure
571 
572   @ref Advanced
573 **/
574 int CeedElemRestrictionGetElementSize(CeedElemRestriction rstr,
575                                       CeedInt *elemsize) {
576   *elemsize = rstr->elemsize;
577   return 0;
578 }
579 
580 /**
581   @brief Get the number of degrees of freedom in the range of a
582          CeedElemRestriction
583 
584   @param rstr             CeedElemRestriction
585   @param[out] numnodes    Variable to store number of nodes
586 
587   @return An error code: 0 - success, otherwise - failure
588 
589   @ref Advanced
590 **/
591 int CeedElemRestrictionGetNumNodes(CeedElemRestriction rstr,
592                                    CeedInt *numnodes) {
593   *numnodes = rstr->nnodes;
594   return 0;
595 }
596 
597 /**
598   @brief Get the number of components in the elements of a
599          CeedElemRestriction
600 
601   @param rstr             CeedElemRestriction
602   @param[out] numcomp     Variable to store number of components
603 
604   @return An error code: 0 - success, otherwise - failure
605 
606   @ref Advanced
607 **/
608 int CeedElemRestrictionGetNumComponents(CeedElemRestriction rstr,
609                                         CeedInt *numcomp) {
610   *numcomp = rstr->ncomp;
611   return 0;
612 }
613 
614 /**
615   @brief Get the number of blocks in a CeedElemRestriction
616 
617   @param rstr             CeedElemRestriction
618   @param[out] numblock    Variable to store number of blocks
619 
620   @return An error code: 0 - success, otherwise - failure
621 
622   @ref Advanced
623 **/
624 int CeedElemRestrictionGetNumBlocks(CeedElemRestriction rstr,
625                                     CeedInt *numblock) {
626   *numblock = rstr->nblk;
627   return 0;
628 }
629 
630 /**
631   @brief Get the size of blocks in the CeedElemRestriction
632 
633   @param rstr             CeedElemRestriction
634   @param[out] blksize     Variable to store size of blocks
635 
636   @return An error code: 0 - success, otherwise - failure
637 
638   @ref Advanced
639 **/
640 int CeedElemRestrictionGetBlockSize(CeedElemRestriction rstr,
641                                     CeedInt *blksize) {
642   *blksize = rstr->blksize;
643   return 0;
644 }
645 
646 /**
647   @brief Get the strides of a strided CeedElemRestriction
648 
649   @param rstr             CeedElemRestriction
650   @param[out] strides     Variable to store strides array
651 
652   @return An error code: 0 - success, otherwise - failure
653 
654   @ref Advanced
655 **/
656 int CeedElemRestrictionGetStrides(CeedElemRestriction rstr,
657                                   CeedInt (*strides)[3]) {
658   if (!rstr->strides)
659     // LCOV_EXCL_START
660     return CeedError(rstr->ceed, 1, "ElemRestriction has no stride data");
661   // LCOV_EXCL_STOP
662 
663   for (int i = 0; i<3; i++)
664     (*strides)[i] = rstr->strides[i];
665   return 0;
666 }
667 
668 /**
669   @brief Get the backend data of a CeedElemRestriction
670 
671   @param rstr             CeedElemRestriction
672   @param[out] data        Variable to store data
673 
674   @return An error code: 0 - success, otherwise - failure
675 
676   @ref Advanced
677 **/
678 int CeedElemRestrictionGetData(CeedElemRestriction rstr, void **data) {
679   *data = rstr->data;
680   return 0;
681 }
682 
683 /**
684   @brief Set the backend data of a CeedElemRestriction
685 
686   @param[out] rstr        CeedElemRestriction
687   @param data             Data to set
688 
689   @return An error code: 0 - success, otherwise - failure
690 
691   @ref Advanced
692 **/
693 int CeedElemRestrictionSetData(CeedElemRestriction rstr, void **data) {
694   rstr->data = *data;
695   return 0;
696 }
697 
698 /**
699   @brief View a CeedElemRestriction
700 
701   @param[in] rstr    CeedElemRestriction to view
702   @param[in] stream  Stream to write; typically stdout/stderr or a file
703 
704   @return Error code: 0 - success, otherwise - failure
705 
706   @ref Utility
707 **/
708 int CeedElemRestrictionView(CeedElemRestriction rstr, FILE *stream) {
709   char stridesstr[500];
710   if (rstr->strides)
711     sprintf(stridesstr, "[%d, %d, %d]", rstr->strides[0], rstr->strides[1],
712             rstr->strides[2]);
713 
714   fprintf(stream, "CeedElemRestriction from (%d, %d) to %d elements with %d "
715           "nodes each and %s %s\n", rstr->nnodes, rstr->ncomp, rstr->nelem,
716           rstr->elemsize, rstr->strides ? "strides" : "L-vector components",
717           rstr->strides ? stridesstr : CeedInterlaceModes[rstr->imode]);
718   return 0;
719 }
720 
721 /**
722   @brief Destroy a CeedElemRestriction
723 
724   @param rstr  CeedElemRestriction to destroy
725 
726   @return An error code: 0 - success, otherwise - failure
727 
728   @ref Basic
729 **/
730 int CeedElemRestrictionDestroy(CeedElemRestriction *rstr) {
731   int ierr;
732 
733   if (!*rstr || --(*rstr)->refcount > 0)
734     return 0;
735   if ((*rstr)->Destroy) {
736     ierr = (*rstr)->Destroy(*rstr); CeedChk(ierr);
737   }
738   ierr = CeedFree(&(*rstr)->strides); CeedChk(ierr);
739   ierr = CeedDestroy(&(*rstr)->ceed); CeedChk(ierr);
740   ierr = CeedFree(rstr); CeedChk(ierr);
741   return 0;
742 }
743 
744 /// @}
745