xref: /libCEED/backends/ref/ceed-ref-operator.c (revision e984cf9ab7e61f88276fc03d915be3267ae350fc)
1 // Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and other CEED contributors.
2 // All Rights Reserved. See the top-level LICENSE and NOTICE files for details.
3 //
4 // SPDX-License-Identifier: BSD-2-Clause
5 //
6 // This file is part of CEED:  http://github.com/ceed
7 
8 #include <ceed.h>
9 #include <ceed/backend.h>
10 #include <stdbool.h>
11 #include <stddef.h>
12 #include <stdint.h>
13 
14 #include "ceed-ref.h"
15 
16 //------------------------------------------------------------------------------
17 // Setup Input/Output Fields
18 //------------------------------------------------------------------------------
19 static int CeedOperatorSetupFields_Ref(CeedQFunction qf, CeedOperator op, bool is_input, CeedVector *e_vecs_full, CeedVector *e_vecs,
20                                        CeedVector *q_vecs, CeedInt start_e, CeedInt num_fields, CeedInt Q) {
21   CeedInt  num_comp, size, P;
22   CeedSize e_size, q_size;
23   Ceed     ceed;
24   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
25   CeedBasis           basis;
26   CeedElemRestriction elem_restr;
27   CeedOperatorField  *op_fields;
28   CeedQFunctionField *qf_fields;
29   if (is_input) {
30     CeedCallBackend(CeedOperatorGetFields(op, NULL, &op_fields, NULL, NULL));
31     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_fields, NULL, NULL));
32   } else {
33     CeedCallBackend(CeedOperatorGetFields(op, NULL, NULL, NULL, &op_fields));
34     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, NULL, NULL, &qf_fields));
35   }
36 
37   // Loop over fields
38   for (CeedInt i = 0; i < num_fields; i++) {
39     CeedEvalMode eval_mode;
40     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_fields[i], &eval_mode));
41 
42     if (eval_mode != CEED_EVAL_WEIGHT) {
43       CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_fields[i], &elem_restr));
44       CeedCallBackend(CeedElemRestrictionCreateVector(elem_restr, NULL, &e_vecs_full[i + start_e]));
45     }
46 
47     switch (eval_mode) {
48       case CEED_EVAL_NONE:
49         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
50         q_size = (CeedSize)Q * size;
51         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
52         break;
53       case CEED_EVAL_INTERP:
54       case CEED_EVAL_GRAD:
55       case CEED_EVAL_DIV:
56       case CEED_EVAL_CURL:
57         CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
58         CeedCallBackend(CeedQFunctionFieldGetSize(qf_fields[i], &size));
59         CeedCallBackend(CeedBasisGetNumNodes(basis, &P));
60         CeedCallBackend(CeedBasisGetNumComponents(basis, &num_comp));
61         e_size = (CeedSize)P * num_comp;
62         CeedCallBackend(CeedVectorCreate(ceed, e_size, &e_vecs[i]));
63         q_size = (CeedSize)Q * size;
64         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
65         break;
66       case CEED_EVAL_WEIGHT:  // Only on input fields
67         CeedCallBackend(CeedOperatorFieldGetBasis(op_fields[i], &basis));
68         q_size = (CeedSize)Q;
69         CeedCallBackend(CeedVectorCreate(ceed, q_size, &q_vecs[i]));
70         CeedCallBackend(CeedBasisApply(basis, 1, CEED_NOTRANSPOSE, CEED_EVAL_WEIGHT, CEED_VECTOR_NONE, q_vecs[i]));
71         break;
72     }
73   }
74   return CEED_ERROR_SUCCESS;
75 }
76 
77 //------------------------------------------------------------------------------
78 // Setup Operator
79 //------------------------------------------------------------------------------/*
80 static int CeedOperatorSetup_Ref(CeedOperator op) {
81   bool is_setup_done;
82   CeedCallBackend(CeedOperatorIsSetupDone(op, &is_setup_done));
83   if (is_setup_done) return CEED_ERROR_SUCCESS;
84   Ceed ceed;
85   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
86   CeedOperator_Ref *impl;
87   CeedCallBackend(CeedOperatorGetData(op, &impl));
88   CeedQFunction qf;
89   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
90   CeedInt Q, num_input_fields, num_output_fields;
91   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
92   CeedCallBackend(CeedQFunctionIsIdentity(qf, &impl->is_identity_qf));
93   CeedOperatorField *op_input_fields, *op_output_fields;
94   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
95   CeedQFunctionField *qf_input_fields, *qf_output_fields;
96   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
97 
98   // Allocate
99   CeedCallBackend(CeedCalloc(num_input_fields + num_output_fields, &impl->e_vecs_full));
100 
101   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->input_states));
102   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->e_vecs_in));
103   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->e_vecs_out));
104   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->q_vecs_in));
105   CeedCallBackend(CeedCalloc(CEED_FIELD_MAX, &impl->q_vecs_out));
106 
107   impl->num_inputs  = num_input_fields;
108   impl->num_outputs = num_output_fields;
109 
110   // Set up infield and outfield e_vecs and q_vecs
111   // Infields
112   CeedCallBackend(CeedOperatorSetupFields_Ref(qf, op, true, impl->e_vecs_full, impl->e_vecs_in, impl->q_vecs_in, 0, num_input_fields, Q));
113   // Outfields
114   CeedCallBackend(
115       CeedOperatorSetupFields_Ref(qf, op, false, impl->e_vecs_full, impl->e_vecs_out, impl->q_vecs_out, num_input_fields, num_output_fields, Q));
116 
117   // Identity QFunctions
118   if (impl->is_identity_qf) {
119     CeedEvalMode        in_mode, out_mode;
120     CeedQFunctionField *in_fields, *out_fields;
121     CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &in_fields, NULL, &out_fields));
122     CeedCallBackend(CeedQFunctionFieldGetEvalMode(in_fields[0], &in_mode));
123     CeedCallBackend(CeedQFunctionFieldGetEvalMode(out_fields[0], &out_mode));
124 
125     if (in_mode == CEED_EVAL_NONE && out_mode == CEED_EVAL_NONE) {
126       impl->is_identity_restr_op = true;
127     } else {
128       CeedCallBackend(CeedVectorReferenceCopy(impl->q_vecs_in[0], &impl->q_vecs_out[0]));
129     }
130   }
131 
132   CeedCallBackend(CeedOperatorSetSetupDone(op));
133 
134   return CEED_ERROR_SUCCESS;
135 }
136 
137 //------------------------------------------------------------------------------
138 // Setup Operator Inputs
139 //------------------------------------------------------------------------------
140 static inline int CeedOperatorSetupInputs_Ref(CeedInt num_input_fields, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
141                                               CeedVector in_vec, const bool skip_active, CeedScalar *e_data_full[2 * CEED_FIELD_MAX],
142                                               CeedOperator_Ref *impl, CeedRequest *request) {
143   CeedEvalMode        eval_mode;
144   CeedVector          vec;
145   CeedElemRestriction elem_restr;
146   uint64_t            state;
147 
148   for (CeedInt i = 0; i < num_input_fields; i++) {
149     // Get input vector
150     CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
151     if (vec == CEED_VECTOR_ACTIVE) {
152       if (skip_active) continue;
153       else vec = in_vec;
154     }
155 
156     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
157     // Restrict and Evec
158     if (eval_mode == CEED_EVAL_WEIGHT) {  // Skip
159     } else {
160       // Restrict
161       CeedCallBackend(CeedVectorGetState(vec, &state));
162       // Skip restriction if input is unchanged
163       if (state != impl->input_states[i] || vec == in_vec) {
164         CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_input_fields[i], &elem_restr));
165         CeedCallBackend(CeedElemRestrictionApply(elem_restr, CEED_NOTRANSPOSE, vec, impl->e_vecs_full[i], request));
166         impl->input_states[i] = state;
167       }
168       // Get evec
169       CeedCallBackend(CeedVectorGetArrayRead(impl->e_vecs_full[i], CEED_MEM_HOST, (const CeedScalar **)&e_data_full[i]));
170     }
171   }
172   return CEED_ERROR_SUCCESS;
173 }
174 
175 //------------------------------------------------------------------------------
176 // Input Basis Action
177 //------------------------------------------------------------------------------
178 static inline int CeedOperatorInputBasis_Ref(CeedInt e, CeedInt Q, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
179                                              CeedInt num_input_fields, const bool skip_active, CeedScalar *e_data_full[2 * CEED_FIELD_MAX],
180                                              CeedOperator_Ref *impl) {
181   CeedInt             elem_size, size, num_comp;
182   CeedElemRestriction elem_restr;
183   CeedEvalMode        eval_mode;
184   CeedBasis           basis;
185 
186   for (CeedInt i = 0; i < num_input_fields; i++) {
187     // Skip active input
188     if (skip_active) {
189       CeedVector vec;
190       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
191       if (vec == CEED_VECTOR_ACTIVE) continue;
192     }
193     // Get elem_size, eval_mode, size
194     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_input_fields[i], &elem_restr));
195     CeedCallBackend(CeedElemRestrictionGetElementSize(elem_restr, &elem_size));
196     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
197     CeedCallBackend(CeedQFunctionFieldGetSize(qf_input_fields[i], &size));
198     // Basis action
199     switch (eval_mode) {
200       case CEED_EVAL_NONE:
201         CeedCallBackend(CeedVectorSetArray(impl->q_vecs_in[i], CEED_MEM_HOST, CEED_USE_POINTER, &e_data_full[i][e * Q * size]));
202         break;
203       case CEED_EVAL_INTERP:
204       case CEED_EVAL_GRAD:
205       case CEED_EVAL_DIV:
206       case CEED_EVAL_CURL:
207         CeedCallBackend(CeedOperatorFieldGetBasis(op_input_fields[i], &basis));
208         CeedCallBackend(CeedBasisGetNumComponents(basis, &num_comp));
209         CeedCallBackend(CeedVectorSetArray(impl->e_vecs_in[i], CEED_MEM_HOST, CEED_USE_POINTER, &e_data_full[i][e * elem_size * num_comp]));
210         CeedCallBackend(CeedBasisApply(basis, 1, CEED_NOTRANSPOSE, eval_mode, impl->e_vecs_in[i], impl->q_vecs_in[i]));
211         break;
212       case CEED_EVAL_WEIGHT:
213         break;  // No action
214     }
215   }
216   return CEED_ERROR_SUCCESS;
217 }
218 
219 //------------------------------------------------------------------------------
220 // Output Basis Action
221 //------------------------------------------------------------------------------
222 static inline int CeedOperatorOutputBasis_Ref(CeedInt e, CeedInt Q, CeedQFunctionField *qf_output_fields, CeedOperatorField *op_output_fields,
223                                               CeedInt num_input_fields, CeedInt num_output_fields, CeedOperator op,
224                                               CeedScalar *e_data_full[2 * CEED_FIELD_MAX], CeedOperator_Ref *impl) {
225   CeedInt             elem_size, num_comp;
226   CeedElemRestriction elem_restr;
227   CeedEvalMode        eval_mode;
228   CeedBasis           basis;
229 
230   for (CeedInt i = 0; i < num_output_fields; i++) {
231     // Get elem_size, eval_mode
232     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[i], &elem_restr));
233     CeedCallBackend(CeedElemRestrictionGetElementSize(elem_restr, &elem_size));
234     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
235     // Basis action
236     switch (eval_mode) {
237       case CEED_EVAL_NONE:
238         break;  // No action
239       case CEED_EVAL_INTERP:
240       case CEED_EVAL_GRAD:
241       case CEED_EVAL_DIV:
242       case CEED_EVAL_CURL:
243         CeedCallBackend(CeedOperatorFieldGetBasis(op_output_fields[i], &basis));
244         CeedCallBackend(CeedBasisGetNumComponents(basis, &num_comp));
245         CeedCallBackend(
246             CeedVectorSetArray(impl->e_vecs_out[i], CEED_MEM_HOST, CEED_USE_POINTER, &e_data_full[i + num_input_fields][e * elem_size * num_comp]));
247         CeedCallBackend(CeedBasisApply(basis, 1, CEED_TRANSPOSE, eval_mode, impl->q_vecs_out[i], impl->e_vecs_out[i]));
248         break;
249       // LCOV_EXCL_START
250       case CEED_EVAL_WEIGHT: {
251         Ceed ceed;
252         CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
253         return CeedError(ceed, CEED_ERROR_BACKEND, "CEED_EVAL_WEIGHT cannot be an output evaluation mode");
254         // LCOV_EXCL_STOP
255       }
256     }
257   }
258   return CEED_ERROR_SUCCESS;
259 }
260 
261 //------------------------------------------------------------------------------
262 // Restore Input Vectors
263 //------------------------------------------------------------------------------
264 static inline int CeedOperatorRestoreInputs_Ref(CeedInt num_input_fields, CeedQFunctionField *qf_input_fields, CeedOperatorField *op_input_fields,
265                                                 const bool skip_active, CeedScalar *e_data_full[2 * CEED_FIELD_MAX], CeedOperator_Ref *impl) {
266   CeedEvalMode eval_mode;
267 
268   for (CeedInt i = 0; i < num_input_fields; i++) {
269     // Skip active inputs
270     if (skip_active) {
271       CeedVector vec;
272       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
273       if (vec == CEED_VECTOR_ACTIVE) continue;
274     }
275     // Restore input
276     CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_input_fields[i], &eval_mode));
277     if (eval_mode == CEED_EVAL_WEIGHT) {  // Skip
278     } else {
279       CeedCallBackend(CeedVectorRestoreArrayRead(impl->e_vecs_full[i], (const CeedScalar **)&e_data_full[i]));
280     }
281   }
282   return CEED_ERROR_SUCCESS;
283 }
284 
285 //------------------------------------------------------------------------------
286 // Operator Apply
287 //------------------------------------------------------------------------------
288 static int CeedOperatorApplyAdd_Ref(CeedOperator op, CeedVector in_vec, CeedVector out_vec, CeedRequest *request) {
289   CeedOperator_Ref *impl;
290   CeedCallBackend(CeedOperatorGetData(op, &impl));
291   CeedQFunction qf;
292   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
293   CeedInt Q, num_elem, num_input_fields, num_output_fields, size;
294   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
295   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
296   CeedOperatorField *op_input_fields, *op_output_fields;
297   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
298   CeedQFunctionField *qf_input_fields, *qf_output_fields;
299   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
300   CeedEvalMode        eval_mode;
301   CeedVector          vec;
302   CeedElemRestriction elem_restr;
303   CeedScalar         *e_data_full[2 * CEED_FIELD_MAX] = {NULL};
304 
305   // Setup
306   CeedCallBackend(CeedOperatorSetup_Ref(op));
307 
308   // Restriction only operator
309   if (impl->is_identity_restr_op) {
310     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_input_fields[0], &elem_restr));
311     CeedCallBackend(CeedElemRestrictionApply(elem_restr, CEED_NOTRANSPOSE, in_vec, impl->e_vecs_full[0], request));
312     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[0], &elem_restr));
313     CeedCallBackend(CeedElemRestrictionApply(elem_restr, CEED_TRANSPOSE, impl->e_vecs_full[0], out_vec, request));
314     return CEED_ERROR_SUCCESS;
315   }
316 
317   // Input Evecs and Restriction
318   CeedCallBackend(CeedOperatorSetupInputs_Ref(num_input_fields, qf_input_fields, op_input_fields, in_vec, false, e_data_full, impl, request));
319 
320   // Output Evecs
321   for (CeedInt i = 0; i < num_output_fields; i++) {
322     CeedCallBackend(CeedVectorGetArrayWrite(impl->e_vecs_full[i + impl->num_inputs], CEED_MEM_HOST, &e_data_full[i + num_input_fields]));
323   }
324 
325   // Loop through elements
326   for (CeedInt e = 0; e < num_elem; e++) {
327     // Output pointers
328     for (CeedInt i = 0; i < num_output_fields; i++) {
329       CeedCallBackend(CeedQFunctionFieldGetEvalMode(qf_output_fields[i], &eval_mode));
330       if (eval_mode == CEED_EVAL_NONE) {
331         CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[i], &size));
332         CeedCallBackend(CeedVectorSetArray(impl->q_vecs_out[i], CEED_MEM_HOST, CEED_USE_POINTER, &e_data_full[i + num_input_fields][e * Q * size]));
333       }
334     }
335 
336     // Input basis apply
337     CeedCallBackend(CeedOperatorInputBasis_Ref(e, Q, qf_input_fields, op_input_fields, num_input_fields, false, e_data_full, impl));
338 
339     // Q function
340     if (!impl->is_identity_qf) {
341       CeedCallBackend(CeedQFunctionApply(qf, Q, impl->q_vecs_in, impl->q_vecs_out));
342     }
343 
344     // Output basis apply
345     CeedCallBackend(
346         CeedOperatorOutputBasis_Ref(e, Q, qf_output_fields, op_output_fields, num_input_fields, num_output_fields, op, e_data_full, impl));
347   }
348 
349   // Output restriction
350   for (CeedInt i = 0; i < num_output_fields; i++) {
351     // Restore Evec
352     CeedCallBackend(CeedVectorRestoreArray(impl->e_vecs_full[i + impl->num_inputs], &e_data_full[i + num_input_fields]));
353     // Get output vector
354     CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[i], &vec));
355     // Active
356     if (vec == CEED_VECTOR_ACTIVE) vec = out_vec;
357     // Restrict
358     CeedCallBackend(CeedOperatorFieldGetElemRestriction(op_output_fields[i], &elem_restr));
359     CeedCallBackend(CeedElemRestrictionApply(elem_restr, CEED_TRANSPOSE, impl->e_vecs_full[i + impl->num_inputs], vec, request));
360   }
361 
362   // Restore input arrays
363   CeedCallBackend(CeedOperatorRestoreInputs_Ref(num_input_fields, qf_input_fields, op_input_fields, false, e_data_full, impl));
364 
365   return CEED_ERROR_SUCCESS;
366 }
367 
368 //------------------------------------------------------------------------------
369 // Core code for assembling linear QFunction
370 //------------------------------------------------------------------------------
371 static inline int CeedOperatorLinearAssembleQFunctionCore_Ref(CeedOperator op, bool build_objects, CeedVector *assembled, CeedElemRestriction *rstr,
372                                                               CeedRequest *request) {
373   Ceed                ceed, ceed_parent;
374   CeedOperator_Ref   *impl;
375   CeedQFunction       qf;
376   CeedQFunctionField *qf_input_fields, *qf_output_fields;
377   CeedOperatorField  *op_input_fields, *op_output_fields;
378   CeedVector          vec, *active_in;
379   CeedInt             num_active_in, num_active_out, Q, num_elem, num_input_fields, num_output_fields, size;
380   CeedSize            q_size;
381   CeedScalar         *a, *tmp, *e_data_full[2 * CEED_FIELD_MAX] = {NULL};
382   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
383   CeedCallBackend(CeedOperatorGetFallbackParentCeed(op, &ceed_parent));
384   CeedCallBackend(CeedOperatorGetData(op, &impl));
385   active_in     = impl->qf_active_in;
386   num_active_in = impl->num_active_in, num_active_out = impl->num_active_out;
387   CeedCallBackend(CeedOperatorGetQFunction(op, &qf));
388   CeedCallBackend(CeedOperatorGetNumQuadraturePoints(op, &Q));
389   CeedCallBackend(CeedOperatorGetNumElements(op, &num_elem));
390   CeedCallBackend(CeedQFunctionGetFields(qf, NULL, &qf_input_fields, NULL, &qf_output_fields));
391   CeedCallBackend(CeedOperatorGetFields(op, &num_input_fields, &op_input_fields, &num_output_fields, &op_output_fields));
392 
393   // Setup
394   CeedCallBackend(CeedOperatorSetup_Ref(op));
395 
396   // Check for identity
397   CeedCheck(!impl->is_identity_qf, ceed, CEED_ERROR_BACKEND, "Assembling identity QFunctions not supported");
398 
399   // Input Evecs and Restriction
400   CeedCallBackend(CeedOperatorSetupInputs_Ref(num_input_fields, qf_input_fields, op_input_fields, NULL, true, e_data_full, impl, request));
401 
402   // Count number of active input fields
403   if (!num_active_in) {
404     for (CeedInt i = 0; i < num_input_fields; i++) {
405       // Get input vector
406       CeedCallBackend(CeedOperatorFieldGetVector(op_input_fields[i], &vec));
407       // Check if active input
408       if (vec == CEED_VECTOR_ACTIVE) {
409         CeedCallBackend(CeedQFunctionFieldGetSize(qf_input_fields[i], &size));
410         CeedCallBackend(CeedVectorSetValue(impl->q_vecs_in[i], 0.0));
411         CeedCallBackend(CeedVectorGetArray(impl->q_vecs_in[i], CEED_MEM_HOST, &tmp));
412         CeedCallBackend(CeedRealloc(num_active_in + size, &active_in));
413         for (CeedInt field = 0; field < size; field++) {
414           q_size = (CeedSize)Q;
415           CeedCallBackend(CeedVectorCreate(ceed, q_size, &active_in[num_active_in + field]));
416           CeedCallBackend(CeedVectorSetArray(active_in[num_active_in + field], CEED_MEM_HOST, CEED_USE_POINTER, &tmp[field * Q]));
417         }
418         num_active_in += size;
419         CeedCallBackend(CeedVectorRestoreArray(impl->q_vecs_in[i], &tmp));
420       }
421     }
422     impl->num_active_in = num_active_in;
423     impl->qf_active_in  = active_in;
424   }
425 
426   // Count number of active output fields
427   if (!num_active_out) {
428     for (CeedInt i = 0; i < num_output_fields; i++) {
429       // Get output vector
430       CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[i], &vec));
431       // Check if active output
432       if (vec == CEED_VECTOR_ACTIVE) {
433         CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[i], &size));
434         num_active_out += size;
435       }
436     }
437     impl->num_active_out = num_active_out;
438   }
439 
440   // Check sizes
441   CeedCheck(num_active_in > 0 && num_active_out > 0, ceed, CEED_ERROR_BACKEND, "Cannot assemble QFunction without active inputs and outputs");
442 
443   // Build objects if needed
444   if (build_objects) {
445     // Create output restriction
446     CeedInt strides[3] = {1, Q, num_active_in * num_active_out * Q}; /* *NOPAD* */
447     CeedCallBackend(CeedElemRestrictionCreateStrided(ceed_parent, num_elem, Q, num_active_in * num_active_out,
448                                                      num_active_in * num_active_out * num_elem * Q, strides, rstr));
449     // Create assembled vector
450     CeedSize l_size = (CeedSize)num_elem * Q * num_active_in * num_active_out;
451     CeedCallBackend(CeedVectorCreate(ceed_parent, l_size, assembled));
452   }
453   // Clear output vector
454   CeedCallBackend(CeedVectorSetValue(*assembled, 0.0));
455   CeedCallBackend(CeedVectorGetArray(*assembled, CEED_MEM_HOST, &a));
456 
457   // Loop through elements
458   for (CeedInt e = 0; e < num_elem; e++) {
459     // Input basis apply
460     CeedCallBackend(CeedOperatorInputBasis_Ref(e, Q, qf_input_fields, op_input_fields, num_input_fields, true, e_data_full, impl));
461 
462     // Assemble QFunction
463     for (CeedInt in = 0; in < num_active_in; in++) {
464       // Set Inputs
465       CeedCallBackend(CeedVectorSetValue(active_in[in], 1.0));
466       if (num_active_in > 1) {
467         CeedCallBackend(CeedVectorSetValue(active_in[(in + num_active_in - 1) % num_active_in], 0.0));
468       }
469       // Set Outputs
470       for (CeedInt out = 0; out < num_output_fields; out++) {
471         // Get output vector
472         CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[out], &vec));
473         // Check if active output
474         if (vec == CEED_VECTOR_ACTIVE) {
475           CeedCallBackend(CeedVectorSetArray(impl->q_vecs_out[out], CEED_MEM_HOST, CEED_USE_POINTER, a));
476           CeedCallBackend(CeedQFunctionFieldGetSize(qf_output_fields[out], &size));
477           a += size * Q;  // Advance the pointer by the size of the output
478         }
479       }
480       // Apply QFunction
481       CeedCallBackend(CeedQFunctionApply(qf, Q, impl->q_vecs_in, impl->q_vecs_out));
482     }
483   }
484 
485   // Un-set output Qvecs to prevent accidental overwrite of Assembled
486   for (CeedInt out = 0; out < num_output_fields; out++) {
487     // Get output vector
488     CeedCallBackend(CeedOperatorFieldGetVector(op_output_fields[out], &vec));
489     // Check if active output
490     if (vec == CEED_VECTOR_ACTIVE && num_elem > 0) {
491       CeedCallBackend(CeedVectorTakeArray(impl->q_vecs_out[out], CEED_MEM_HOST, NULL));
492     }
493   }
494 
495   // Restore input arrays
496   CeedCallBackend(CeedOperatorRestoreInputs_Ref(num_input_fields, qf_input_fields, op_input_fields, true, e_data_full, impl));
497 
498   // Restore output
499   CeedCallBackend(CeedVectorRestoreArray(*assembled, &a));
500 
501   return CEED_ERROR_SUCCESS;
502 }
503 
504 //------------------------------------------------------------------------------
505 // Assemble Linear QFunction
506 //------------------------------------------------------------------------------
507 static int CeedOperatorLinearAssembleQFunction_Ref(CeedOperator op, CeedVector *assembled, CeedElemRestriction *rstr, CeedRequest *request) {
508   return CeedOperatorLinearAssembleQFunctionCore_Ref(op, true, assembled, rstr, request);
509 }
510 
511 //------------------------------------------------------------------------------
512 // Update Assembled Linear QFunction
513 //------------------------------------------------------------------------------
514 static int CeedOperatorLinearAssembleQFunctionUpdate_Ref(CeedOperator op, CeedVector assembled, CeedElemRestriction rstr, CeedRequest *request) {
515   return CeedOperatorLinearAssembleQFunctionCore_Ref(op, false, &assembled, &rstr, request);
516 }
517 
518 //------------------------------------------------------------------------------
519 // Operator Destroy
520 //------------------------------------------------------------------------------
521 static int CeedOperatorDestroy_Ref(CeedOperator op) {
522   CeedOperator_Ref *impl;
523   CeedCallBackend(CeedOperatorGetData(op, &impl));
524 
525   for (CeedInt i = 0; i < impl->num_inputs + impl->num_outputs; i++) {
526     CeedCallBackend(CeedVectorDestroy(&impl->e_vecs_full[i]));
527   }
528   CeedCallBackend(CeedFree(&impl->e_vecs_full));
529   CeedCallBackend(CeedFree(&impl->input_states));
530 
531   for (CeedInt i = 0; i < impl->num_inputs; i++) {
532     CeedCallBackend(CeedVectorDestroy(&impl->e_vecs_in[i]));
533     CeedCallBackend(CeedVectorDestroy(&impl->q_vecs_in[i]));
534   }
535   CeedCallBackend(CeedFree(&impl->e_vecs_in));
536   CeedCallBackend(CeedFree(&impl->q_vecs_in));
537 
538   for (CeedInt i = 0; i < impl->num_outputs; i++) {
539     CeedCallBackend(CeedVectorDestroy(&impl->e_vecs_out[i]));
540     CeedCallBackend(CeedVectorDestroy(&impl->q_vecs_out[i]));
541   }
542   CeedCallBackend(CeedFree(&impl->e_vecs_out));
543   CeedCallBackend(CeedFree(&impl->q_vecs_out));
544 
545   // QFunction assembly
546   for (CeedInt i = 0; i < impl->num_active_in; i++) {
547     CeedCallBackend(CeedVectorDestroy(&impl->qf_active_in[i]));
548   }
549   CeedCallBackend(CeedFree(&impl->qf_active_in));
550 
551   CeedCallBackend(CeedFree(&impl));
552   return CEED_ERROR_SUCCESS;
553 }
554 
555 //------------------------------------------------------------------------------
556 // Operator Create
557 //------------------------------------------------------------------------------
558 int CeedOperatorCreate_Ref(CeedOperator op) {
559   Ceed ceed;
560   CeedCallBackend(CeedOperatorGetCeed(op, &ceed));
561   CeedOperator_Ref *impl;
562 
563   CeedCallBackend(CeedCalloc(1, &impl));
564   CeedCallBackend(CeedOperatorSetData(op, impl));
565 
566   CeedCallBackend(CeedSetBackendFunction(ceed, "Operator", op, "LinearAssembleQFunction", CeedOperatorLinearAssembleQFunction_Ref));
567   CeedCallBackend(CeedSetBackendFunction(ceed, "Operator", op, "LinearAssembleQFunctionUpdate", CeedOperatorLinearAssembleQFunctionUpdate_Ref));
568   CeedCallBackend(CeedSetBackendFunction(ceed, "Operator", op, "ApplyAdd", CeedOperatorApplyAdd_Ref));
569   CeedCallBackend(CeedSetBackendFunction(ceed, "Operator", op, "Destroy", CeedOperatorDestroy_Ref));
570   return CEED_ERROR_SUCCESS;
571 }
572 
573 //------------------------------------------------------------------------------
574