xref: /petsc/include/petscdt.h (revision 21e3ffae2f3b73c0bd738cf6d0a809700fc04bb0)
1 /*
2   Common tools for constructing discretizations
3 */
4 #ifndef PETSCDT_H
5 #define PETSCDT_H
6 
7 #include <petscsys.h>
8 
9 /* SUBMANSEC = DT */
10 
11 PETSC_EXTERN PetscClassId PETSCQUADRATURE_CLASSID;
12 
13 /*S
14   PetscQuadrature - Quadrature rule for integration.
15 
16   Level: beginner
17 
18 .seealso: `PetscQuadratureCreate()`, `PetscQuadratureDestroy()`
19 S*/
20 typedef struct _p_PetscQuadrature *PetscQuadrature;
21 
22 /*E
23   PetscGaussLobattoLegendreCreateType - algorithm used to compute the Gauss-Lobatto-Legendre nodes and weights
24 
25   Level: intermediate
26 
27 $  `PETSCGAUSSLOBATTOLEGENDRE_VIA_LINEAR_ALGEBRA` - compute the nodes via linear algebra
28 $  `PETSCGAUSSLOBATTOLEGENDRE_VIA_NEWTON` - compute the nodes by solving a nonlinear equation with Newton's method
29 
30 E*/
31 typedef enum {
32   PETSCGAUSSLOBATTOLEGENDRE_VIA_LINEAR_ALGEBRA,
33   PETSCGAUSSLOBATTOLEGENDRE_VIA_NEWTON
34 } PetscGaussLobattoLegendreCreateType;
35 
36 /*E
37   PetscDTNodeType - A description of strategies for generating nodes (both
38   quadrature nodes and nodes for Lagrange polynomials)
39 
40   Level: intermediate
41 
42 $  `PETSCDTNODES_DEFAULT` - Nodes chosen by PETSc
43 $  `PETSCDTNODES_GAUSSJACOBI` - Nodes at either Gauss-Jacobi or Gauss-Lobatto-Jacobi quadrature points
44 $  `PETSCDTNODES_EQUISPACED` - Nodes equispaced either including the endpoints or excluding them
45 $  `PETSCDTNODES_TANHSINH` - Nodes at Tanh-Sinh quadrature points
46 
47   Note:
48   A `PetscDTNodeType` can be paired with a `PetscBool` to indicate whether
49   the nodes include endpoints or not, and in the case of `PETSCDT_GAUSSJACOBI`
50   with exponents for the weight function.
51 
52 E*/
53 typedef enum {
54   PETSCDTNODES_DEFAULT = -1,
55   PETSCDTNODES_GAUSSJACOBI,
56   PETSCDTNODES_EQUISPACED,
57   PETSCDTNODES_TANHSINH
58 } PetscDTNodeType;
59 
60 PETSC_EXTERN const char *const *const PetscDTNodeTypes;
61 
62 /*E
63   PetscDTSimplexQuadratureType - A description of classes of quadrature rules for simplices
64 
65   Level: intermediate
66 
67 $  `PETSCDTSIMPLEXQUAD_DEFAULT` - Quadrature rule chosen by PETSc
68 $  `PETSCDTSIMPLEXQUAD_CONIC`   - Quadrature rules constructed as
69                                 conically-warped tensor products of 1D
70                                 Gauss-Jacobi quadrature rules.  These are
71                                 explicitly computable in any dimension for any
72                                 degree, and the tensor-product structure can be
73                                 exploited by sum-factorization methods, but
74                                 they are not efficient in terms of nodes per
75                                 polynomial degree.
76 $  `PETSCDTSIMPLEXQUAD_MINSYM`  - Quadrature rules that are fully symmetric
77                                 (symmetries of the simplex preserve the nodes
78                                 and weights) with minimal (or near minimal)
79                                 number of nodes.  In dimensions higher than 1
80                                 these are not simple to compute, so lookup
81                                 tables are used.
82 
83 .seealso: `PetscDTSimplexQuadrature()`
84 E*/
85 typedef enum {
86   PETSCDTSIMPLEXQUAD_DEFAULT = -1,
87   PETSCDTSIMPLEXQUAD_CONIC   = 0,
88   PETSCDTSIMPLEXQUAD_MINSYM
89 } PetscDTSimplexQuadratureType;
90 
91 PETSC_EXTERN const char *const *const PetscDTSimplexQuadratureTypes;
92 
93 PETSC_EXTERN PetscErrorCode PetscQuadratureCreate(MPI_Comm, PetscQuadrature *);
94 PETSC_EXTERN PetscErrorCode PetscQuadratureDuplicate(PetscQuadrature, PetscQuadrature *);
95 PETSC_EXTERN PetscErrorCode PetscQuadratureGetOrder(PetscQuadrature, PetscInt *);
96 PETSC_EXTERN PetscErrorCode PetscQuadratureSetOrder(PetscQuadrature, PetscInt);
97 PETSC_EXTERN PetscErrorCode PetscQuadratureGetNumComponents(PetscQuadrature, PetscInt *);
98 PETSC_EXTERN PetscErrorCode PetscQuadratureSetNumComponents(PetscQuadrature, PetscInt);
99 PETSC_EXTERN PetscErrorCode PetscQuadratureEqual(PetscQuadrature, PetscQuadrature, PetscBool *);
100 PETSC_EXTERN PetscErrorCode PetscQuadratureGetData(PetscQuadrature, PetscInt *, PetscInt *, PetscInt *, const PetscReal *[], const PetscReal *[]);
101 PETSC_EXTERN PetscErrorCode PetscQuadratureSetData(PetscQuadrature, PetscInt, PetscInt, PetscInt, const PetscReal[], const PetscReal[]);
102 PETSC_EXTERN PetscErrorCode PetscQuadratureView(PetscQuadrature, PetscViewer);
103 PETSC_EXTERN PetscErrorCode PetscQuadratureDestroy(PetscQuadrature *);
104 
105 PETSC_EXTERN PetscErrorCode PetscDTTensorQuadratureCreate(PetscQuadrature, PetscQuadrature, PetscQuadrature *);
106 PETSC_EXTERN PetscErrorCode PetscQuadratureExpandComposite(PetscQuadrature, PetscInt, const PetscReal[], const PetscReal[], PetscQuadrature *);
107 
108 PETSC_EXTERN PetscErrorCode PetscQuadraturePushForward(PetscQuadrature, PetscInt, const PetscReal[], const PetscReal[], const PetscReal[], PetscInt, PetscQuadrature *);
109 
110 PETSC_EXTERN PetscErrorCode PetscDTLegendreEval(PetscInt, const PetscReal *, PetscInt, const PetscInt *, PetscReal *, PetscReal *, PetscReal *);
111 PETSC_EXTERN PetscErrorCode PetscDTJacobiNorm(PetscReal, PetscReal, PetscInt, PetscReal *);
112 PETSC_EXTERN PetscErrorCode PetscDTJacobiEval(PetscInt, PetscReal, PetscReal, const PetscReal *, PetscInt, const PetscInt *, PetscReal *, PetscReal *, PetscReal *);
113 PETSC_EXTERN PetscErrorCode PetscDTJacobiEvalJet(PetscReal, PetscReal, PetscInt, const PetscReal[], PetscInt, PetscInt, PetscReal[]);
114 PETSC_EXTERN PetscErrorCode PetscDTPKDEvalJet(PetscInt, PetscInt, const PetscReal[], PetscInt, PetscInt, PetscReal[]);
115 PETSC_EXTERN PetscErrorCode PetscDTPTrimmedSize(PetscInt, PetscInt, PetscInt, PetscInt *);
116 PETSC_EXTERN PetscErrorCode PetscDTPTrimmedEvalJet(PetscInt, PetscInt, const PetscReal[], PetscInt, PetscInt, PetscInt, PetscReal[]);
117 PETSC_EXTERN PetscErrorCode PetscDTGaussQuadrature(PetscInt, PetscReal, PetscReal, PetscReal *, PetscReal *);
118 PETSC_EXTERN PetscErrorCode PetscDTGaussJacobiQuadrature(PetscInt, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal *, PetscReal *);
119 PETSC_EXTERN PetscErrorCode PetscDTGaussLobattoJacobiQuadrature(PetscInt, PetscReal, PetscReal, PetscReal, PetscReal, PetscReal *, PetscReal *);
120 PETSC_EXTERN PetscErrorCode PetscDTGaussLobattoLegendreQuadrature(PetscInt, PetscGaussLobattoLegendreCreateType, PetscReal *, PetscReal *);
121 PETSC_EXTERN PetscErrorCode PetscDTReconstructPoly(PetscInt, PetscInt, const PetscReal *, PetscInt, const PetscReal *, PetscReal *);
122 PETSC_EXTERN PetscErrorCode PetscDTGaussTensorQuadrature(PetscInt, PetscInt, PetscInt, PetscReal, PetscReal, PetscQuadrature *);
123 PETSC_EXTERN PetscErrorCode PetscDTStroudConicalQuadrature(PetscInt, PetscInt, PetscInt, PetscReal, PetscReal, PetscQuadrature *);
124 PETSC_EXTERN PetscErrorCode PetscDTSimplexQuadrature(PetscInt, PetscInt, PetscDTSimplexQuadratureType, PetscQuadrature *);
125 
126 PETSC_EXTERN PetscErrorCode PetscDTTanhSinhTensorQuadrature(PetscInt, PetscInt, PetscReal, PetscReal, PetscQuadrature *);
127 PETSC_EXTERN PetscErrorCode PetscDTTanhSinhIntegrate(void (*)(const PetscReal[], void *, PetscReal *), PetscReal, PetscReal, PetscInt, void *, PetscReal *);
128 PETSC_EXTERN PetscErrorCode PetscDTTanhSinhIntegrateMPFR(void (*)(const PetscReal[], void *, PetscReal *), PetscReal, PetscReal, PetscInt, void *, PetscReal *);
129 
130 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreIntegrate(PetscInt, PetscReal *, PetscReal *, const PetscReal *, PetscReal *);
131 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementLaplacianCreate(PetscInt, PetscReal *, PetscReal *, PetscReal ***);
132 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementLaplacianDestroy(PetscInt, PetscReal *, PetscReal *, PetscReal ***);
133 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementGradientCreate(PetscInt, PetscReal *, PetscReal *, PetscReal ***, PetscReal ***);
134 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementGradientDestroy(PetscInt, PetscReal *, PetscReal *, PetscReal ***, PetscReal ***);
135 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementAdvectionCreate(PetscInt, PetscReal *, PetscReal *, PetscReal ***);
136 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementAdvectionDestroy(PetscInt, PetscReal *, PetscReal *, PetscReal ***);
137 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementMassCreate(PetscInt, PetscReal *, PetscReal *, PetscReal ***);
138 PETSC_EXTERN PetscErrorCode PetscGaussLobattoLegendreElementMassDestroy(PetscInt, PetscReal *, PetscReal *, PetscReal ***);
139 
140 PETSC_EXTERN PetscErrorCode PetscDTAltVApply(PetscInt, PetscInt, const PetscReal *, const PetscReal *, PetscReal *);
141 PETSC_EXTERN PetscErrorCode PetscDTAltVWedge(PetscInt, PetscInt, PetscInt, const PetscReal *, const PetscReal *, PetscReal *);
142 PETSC_EXTERN PetscErrorCode PetscDTAltVWedgeMatrix(PetscInt, PetscInt, PetscInt, const PetscReal *, PetscReal *);
143 PETSC_EXTERN PetscErrorCode PetscDTAltVPullback(PetscInt, PetscInt, const PetscReal *, PetscInt, const PetscReal *, PetscReal *);
144 PETSC_EXTERN PetscErrorCode PetscDTAltVPullbackMatrix(PetscInt, PetscInt, const PetscReal *, PetscInt, PetscReal *);
145 PETSC_EXTERN PetscErrorCode PetscDTAltVInterior(PetscInt, PetscInt, const PetscReal *, const PetscReal *, PetscReal *);
146 PETSC_EXTERN PetscErrorCode PetscDTAltVInteriorMatrix(PetscInt, PetscInt, const PetscReal *, PetscReal *);
147 PETSC_EXTERN PetscErrorCode PetscDTAltVInteriorPattern(PetscInt, PetscInt, PetscInt (*)[3]);
148 PETSC_EXTERN PetscErrorCode PetscDTAltVStar(PetscInt, PetscInt, PetscInt, const PetscReal *, PetscReal *);
149 
150 PETSC_EXTERN PetscErrorCode PetscDTBaryToIndex(PetscInt, PetscInt, const PetscInt[], PetscInt *);
151 PETSC_EXTERN PetscErrorCode PetscDTIndexToBary(PetscInt, PetscInt, PetscInt, PetscInt[]);
152 PETSC_EXTERN PetscErrorCode PetscDTGradedOrderToIndex(PetscInt, const PetscInt[], PetscInt *);
153 PETSC_EXTERN PetscErrorCode PetscDTIndexToGradedOrder(PetscInt, PetscInt, PetscInt[]);
154 
155 #if defined(PETSC_USE_64BIT_INDICES)
156   #define PETSC_FACTORIAL_MAX 20
157   #define PETSC_BINOMIAL_MAX  61
158 #else
159   #define PETSC_FACTORIAL_MAX 12
160   #define PETSC_BINOMIAL_MAX  29
161 #endif
162 
163 /*MC
164    PetscDTFactorial - Approximate n! as a real number
165 
166    Input Parameter:
167 .  n - a non-negative integer
168 
169    Output Parameter:
170 .  factorial - n!
171 
172    Level: beginner
173 M*/
174 static inline PetscErrorCode PetscDTFactorial(PetscInt n, PetscReal *factorial)
175 {
176   PetscReal f = 1.0;
177 
178   PetscFunctionBegin;
179   *factorial = -1.0;
180   PetscCheck(n >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Factorial called with negative number %" PetscInt_FMT, n);
181   for (PetscInt i = 1; i < n + 1; ++i) f *= (PetscReal)i;
182   *factorial = f;
183   PetscFunctionReturn(PETSC_SUCCESS);
184 }
185 
186 /*MC
187    PetscDTFactorialInt - Compute n! as an integer
188 
189    Input Parameter:
190 .  n - a non-negative integer
191 
192    Output Parameter:
193 .  factorial - n!
194 
195    Level: beginner
196 
197    Note: this is limited to n such that n! can be represented by PetscInt, which is 12 if PetscInt is a signed 32-bit integer and 20 if PetscInt is a signed 64-bit integer.
198 M*/
199 static inline PetscErrorCode PetscDTFactorialInt(PetscInt n, PetscInt *factorial)
200 {
201   PetscInt facLookup[13] = {1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600};
202 
203   PetscFunctionBegin;
204   *factorial = -1;
205   PetscCheck(n >= 0 && n <= PETSC_FACTORIAL_MAX, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Number of elements %" PetscInt_FMT " is not in supported range [0,%d]", n, PETSC_FACTORIAL_MAX);
206   if (n <= 12) {
207     *factorial = facLookup[n];
208   } else {
209     PetscInt f = facLookup[12];
210     PetscInt i;
211 
212     for (i = 13; i < n + 1; ++i) f *= i;
213     *factorial = f;
214   }
215   PetscFunctionReturn(PETSC_SUCCESS);
216 }
217 
218 /*MC
219    PetscDTBinomial - Approximate the binomial coefficient "n choose k"
220 
221    Input Parameters:
222 +  n - a non-negative integer
223 -  k - an integer between 0 and n, inclusive
224 
225    Output Parameter:
226 .  binomial - approximation of the binomial coefficient n choose k
227 
228    Level: beginner
229 M*/
230 static inline PetscErrorCode PetscDTBinomial(PetscInt n, PetscInt k, PetscReal *binomial)
231 {
232   PetscFunctionBeginHot;
233   *binomial = -1.0;
234   PetscCheck(n >= 0 && k >= 0 && k <= n, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Binomial arguments (%" PetscInt_FMT " %" PetscInt_FMT ") must be non-negative, k <= n", n, k);
235   if (n <= 3) {
236     PetscInt binomLookup[4][4] = {
237       {1, 0, 0, 0},
238       {1, 1, 0, 0},
239       {1, 2, 1, 0},
240       {1, 3, 3, 1}
241     };
242 
243     *binomial = (PetscReal)binomLookup[n][k];
244   } else {
245     PetscReal binom = 1.0;
246 
247     k = PetscMin(k, n - k);
248     for (PetscInt i = 0; i < k; i++) binom = (binom * (PetscReal)(n - i)) / (PetscReal)(i + 1);
249     *binomial = binom;
250   }
251   PetscFunctionReturn(PETSC_SUCCESS);
252 }
253 
254 /*MC
255    PetscDTBinomialInt - Compute the binomial coefficient "n choose k"
256 
257    Input Parameters:
258 +  n - a non-negative integer
259 -  k - an integer between 0 and n, inclusive
260 
261    Output Parameter:
262 .  binomial - the binomial coefficient n choose k
263 
264    Note: this is limited by integers that can be represented by `PetscInt`
265 
266    Level: beginner
267 M*/
268 static inline PetscErrorCode PetscDTBinomialInt(PetscInt n, PetscInt k, PetscInt *binomial)
269 {
270   PetscInt bin;
271 
272   PetscFunctionBegin;
273   *binomial = -1;
274   PetscCheck(n >= 0 && k >= 0 && k <= n, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Binomial arguments (%" PetscInt_FMT " %" PetscInt_FMT ") must be non-negative, k <= n", n, k);
275   PetscCheck(n <= PETSC_BINOMIAL_MAX, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Binomial elements %" PetscInt_FMT " is larger than max for PetscInt, %d", n, PETSC_BINOMIAL_MAX);
276   if (n <= 3) {
277     PetscInt binomLookup[4][4] = {
278       {1, 0, 0, 0},
279       {1, 1, 0, 0},
280       {1, 2, 1, 0},
281       {1, 3, 3, 1}
282     };
283 
284     bin = binomLookup[n][k];
285   } else {
286     PetscInt binom = 1;
287 
288     k = PetscMin(k, n - k);
289     for (PetscInt i = 0; i < k; i++) binom = (binom * (n - i)) / (i + 1);
290     bin = binom;
291   }
292   *binomial = bin;
293   PetscFunctionReturn(PETSC_SUCCESS);
294 }
295 
296 /*MC
297    PetscDTEnumPerm - Get a permutation of n integers from its encoding into the integers [0, n!) as a sequence of swaps.
298 
299    A permutation can be described by the operations that convert the lists [0, 1, ..., n-1] into the permutation,
300    by a sequence of swaps, where the ith step swaps whatever number is in ith position with a number that is in
301    some position j >= i.  This swap is encoded as the difference (j - i).  The difference d_i at step i is less than
302    (n - i).  This sequence of n-1 differences [d_0, ..., d_{n-2}] is encoded as the number
303    (n-1)! * d_0 + (n-2)! * d_1 + ... + 1! * d_{n-2}.
304 
305    Input Parameters:
306 +  n - a non-negative integer (see note about limits below)
307 -  k - an integer in [0, n!)
308 
309    Output Parameters:
310 +  perm - the permuted list of the integers [0, ..., n-1]
311 -  isOdd - if not NULL, returns whether the permutation used an even or odd number of swaps.
312 
313    Note:
314    Limited to n such that n! can be represented by `PetscInt`, which is 12 if `PetscInt` is a signed 32-bit integer and 20 if `PetscInt` is a signed 64-bit integer.
315 
316    Level: beginner
317 M*/
318 static inline PetscErrorCode PetscDTEnumPerm(PetscInt n, PetscInt k, PetscInt *perm, PetscBool *isOdd)
319 {
320   PetscInt  odd = 0;
321   PetscInt  i;
322   PetscInt  work[PETSC_FACTORIAL_MAX];
323   PetscInt *w;
324 
325   PetscFunctionBegin;
326   if (isOdd) *isOdd = PETSC_FALSE;
327   PetscCheck(n >= 0 && n <= PETSC_FACTORIAL_MAX, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Number of elements %" PetscInt_FMT " is not in supported range [0,%d]", n, PETSC_FACTORIAL_MAX);
328   w = &work[n - 2];
329   for (i = 2; i <= n; i++) {
330     *(w--) = k % i;
331     k /= i;
332   }
333   for (i = 0; i < n; i++) perm[i] = i;
334   for (i = 0; i < n - 1; i++) {
335     PetscInt s    = work[i];
336     PetscInt swap = perm[i];
337 
338     perm[i]     = perm[i + s];
339     perm[i + s] = swap;
340     odd ^= (!!s);
341   }
342   if (isOdd) *isOdd = odd ? PETSC_TRUE : PETSC_FALSE;
343   PetscFunctionReturn(PETSC_SUCCESS);
344 }
345 
346 /*MC
347    PetscDTPermIndex - Encode a permutation of n into an integer in [0, n!).  This inverts `PetscDTEnumPerm`.
348 
349    Input Parameters:
350 +  n - a non-negative integer (see note about limits below)
351 -  perm - the permuted list of the integers [0, ..., n-1]
352 
353    Output Parameters:
354 +  k - an integer in [0, n!)
355 -  isOdd - if not NULL, returns whether the permutation used an even or odd number of swaps.
356 
357    Note:
358    Limited to n such that n! can be represented by `PetscInt`, which is 12 if `PetscInt` is a signed 32-bit integer and 20 if `PetscInt` is a signed 64-bit integer.
359 
360    Level: beginner
361 M*/
362 static inline PetscErrorCode PetscDTPermIndex(PetscInt n, const PetscInt *perm, PetscInt *k, PetscBool *isOdd)
363 {
364   PetscInt odd = 0;
365   PetscInt i, idx;
366   PetscInt work[PETSC_FACTORIAL_MAX];
367   PetscInt iwork[PETSC_FACTORIAL_MAX];
368 
369   PetscFunctionBeginHot;
370   *k = -1;
371   if (isOdd) *isOdd = PETSC_FALSE;
372   PetscCheck(n >= 0 && n <= PETSC_FACTORIAL_MAX, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Number of elements %" PetscInt_FMT " is not in supported range [0,%d]", n, PETSC_FACTORIAL_MAX);
373   for (i = 0; i < n; i++) work[i] = i;  /* partial permutation */
374   for (i = 0; i < n; i++) iwork[i] = i; /* partial permutation inverse */
375   for (idx = 0, i = 0; i < n - 1; i++) {
376     PetscInt j    = perm[i];
377     PetscInt icur = work[i];
378     PetscInt jloc = iwork[j];
379     PetscInt diff = jloc - i;
380 
381     idx = idx * (n - i) + diff;
382     /* swap (i, jloc) */
383     work[i]     = j;
384     work[jloc]  = icur;
385     iwork[j]    = i;
386     iwork[icur] = jloc;
387     odd ^= (!!diff);
388   }
389   *k = idx;
390   if (isOdd) *isOdd = odd ? PETSC_TRUE : PETSC_FALSE;
391   PetscFunctionReturn(PETSC_SUCCESS);
392 }
393 
394 /*MC
395    PetscDTEnumSubset - Get an ordered subset of the integers [0, ..., n - 1] from its encoding as an integers in [0, n choose k).
396    The encoding is in lexicographic order.
397 
398    Input Parameters:
399 +  n - a non-negative integer (see note about limits below)
400 .  k - an integer in [0, n]
401 -  j - an index in [0, n choose k)
402 
403    Output Parameter:
404 .  subset - the jth subset of size k of the integers [0, ..., n - 1]
405 
406    Note:
407    Limited by arguments such that n choose k can be represented by `PetscInt`
408 
409    Level: beginner
410 
411 .seealso: `PetscDTSubsetIndex()`
412 M*/
413 static inline PetscErrorCode PetscDTEnumSubset(PetscInt n, PetscInt k, PetscInt j, PetscInt *subset)
414 {
415   PetscInt Nk;
416 
417   PetscFunctionBeginHot;
418   PetscCall(PetscDTBinomialInt(n, k, &Nk));
419   for (PetscInt i = 0, l = 0; i < n && l < k; i++) {
420     PetscInt Nminuskminus = (Nk * (k - l)) / (n - i);
421     PetscInt Nminusk      = Nk - Nminuskminus;
422 
423     if (j < Nminuskminus) {
424       subset[l++] = i;
425       Nk          = Nminuskminus;
426     } else {
427       j -= Nminuskminus;
428       Nk = Nminusk;
429     }
430   }
431   PetscFunctionReturn(PETSC_SUCCESS);
432 }
433 
434 /*MC
435    PetscDTSubsetIndex - Convert an ordered subset of k integers from the set [0, ..., n - 1] to its encoding as an integers in [0, n choose k) in lexicographic order.
436    This is the inverse of `PetscDTEnumSubset`.
437 
438    Input Parameters:
439 +  n - a non-negative integer (see note about limits below)
440 .  k - an integer in [0, n]
441 -  subset - an ordered subset of the integers [0, ..., n - 1]
442 
443    Output Parameter:
444 .  index - the rank of the subset in lexicographic order
445 
446    Note:
447    Limited by arguments such that n choose k can be represented by `PetscInt`
448 
449    Level: beginner
450 
451 .seealso: `PetscDTEnumSubset()`
452 M*/
453 static inline PetscErrorCode PetscDTSubsetIndex(PetscInt n, PetscInt k, const PetscInt *subset, PetscInt *index)
454 {
455   PetscInt j = 0, Nk;
456 
457   PetscFunctionBegin;
458   *index = -1;
459   PetscCall(PetscDTBinomialInt(n, k, &Nk));
460   for (PetscInt i = 0, l = 0; i < n && l < k; i++) {
461     PetscInt Nminuskminus = (Nk * (k - l)) / (n - i);
462     PetscInt Nminusk      = Nk - Nminuskminus;
463 
464     if (subset[l] == i) {
465       l++;
466       Nk = Nminuskminus;
467     } else {
468       j += Nminuskminus;
469       Nk = Nminusk;
470     }
471   }
472   *index = j;
473   PetscFunctionReturn(PETSC_SUCCESS);
474 }
475 
476 /*MC
477    PetscDTEnumSubset - Split the integers [0, ..., n - 1] into two complementary ordered subsets, the first subset of size k and being the jth subset of that size in lexicographic order.
478 
479    Input Parameters:
480 +  n - a non-negative integer (see note about limits below)
481 .  k - an integer in [0, n]
482 -  j - an index in [0, n choose k)
483 
484    Output Parameters:
485 +  perm - the jth subset of size k of the integers [0, ..., n - 1], followed by its complementary set.
486 -  isOdd - if not NULL, return whether perm is an even or odd permutation.
487 
488    Note:
489    Limited by arguments such that n choose k can be represented by `PetscInt`
490 
491    Level: beginner
492 
493 .seealso: `PetscDTEnumSubset()`, `PetscDTSubsetIndex()`
494 M*/
495 static inline PetscErrorCode PetscDTEnumSplit(PetscInt n, PetscInt k, PetscInt j, PetscInt *perm, PetscBool *isOdd)
496 {
497   PetscInt  i, l, m, Nk, odd = 0;
498   PetscInt *subcomp = perm + k;
499 
500   PetscFunctionBegin;
501   if (isOdd) *isOdd = PETSC_FALSE;
502   PetscCall(PetscDTBinomialInt(n, k, &Nk));
503   for (i = 0, l = 0, m = 0; i < n && l < k; i++) {
504     PetscInt Nminuskminus = (Nk * (k - l)) / (n - i);
505     PetscInt Nminusk      = Nk - Nminuskminus;
506 
507     if (j < Nminuskminus) {
508       perm[l++] = i;
509       Nk        = Nminuskminus;
510     } else {
511       subcomp[m++] = i;
512       j -= Nminuskminus;
513       odd ^= ((k - l) & 1);
514       Nk = Nminusk;
515     }
516   }
517   for (; i < n; i++) subcomp[m++] = i;
518   if (isOdd) *isOdd = odd ? PETSC_TRUE : PETSC_FALSE;
519   PetscFunctionReturn(PETSC_SUCCESS);
520 }
521 
522 struct _p_PetscTabulation {
523   PetscInt    K;    /* Indicates a k-jet, namely tabulated derivatives up to order k */
524   PetscInt    Nr;   /* The number of tabulation replicas (often 1) */
525   PetscInt    Np;   /* The number of tabulation points in a replica */
526   PetscInt    Nb;   /* The number of functions tabulated */
527   PetscInt    Nc;   /* The number of function components */
528   PetscInt    cdim; /* The coordinate dimension */
529   PetscReal **T;    /* The tabulation T[K] of functions and their derivatives
530                        T[0] = B[Nr*Np][Nb][Nc]:             The basis function values at quadrature points
531                        T[1] = D[Nr*Np][Nb][Nc][cdim]:       The basis function derivatives at quadrature points
532                        T[2] = H[Nr*Np][Nb][Nc][cdim][cdim]: The basis function second derivatives at quadrature points */
533 };
534 typedef struct _p_PetscTabulation *PetscTabulation;
535 
536 typedef PetscErrorCode (*PetscProbFunc)(const PetscReal[], const PetscReal[], PetscReal[]);
537 
538 typedef enum {
539   DTPROB_DENSITY_CONSTANT,
540   DTPROB_DENSITY_GAUSSIAN,
541   DTPROB_DENSITY_MAXWELL_BOLTZMANN,
542   DTPROB_NUM_DENSITY
543 } DTProbDensityType;
544 PETSC_EXTERN const char *const DTProbDensityTypes[];
545 
546 PETSC_EXTERN PetscErrorCode PetscPDFMaxwellBoltzmann1D(const PetscReal[], const PetscReal[], PetscReal[]);
547 PETSC_EXTERN PetscErrorCode PetscCDFMaxwellBoltzmann1D(const PetscReal[], const PetscReal[], PetscReal[]);
548 PETSC_EXTERN PetscErrorCode PetscPDFMaxwellBoltzmann2D(const PetscReal[], const PetscReal[], PetscReal[]);
549 PETSC_EXTERN PetscErrorCode PetscCDFMaxwellBoltzmann2D(const PetscReal[], const PetscReal[], PetscReal[]);
550 PETSC_EXTERN PetscErrorCode PetscPDFMaxwellBoltzmann3D(const PetscReal[], const PetscReal[], PetscReal[]);
551 PETSC_EXTERN PetscErrorCode PetscCDFMaxwellBoltzmann3D(const PetscReal[], const PetscReal[], PetscReal[]);
552 PETSC_EXTERN PetscErrorCode PetscPDFGaussian1D(const PetscReal[], const PetscReal[], PetscReal[]);
553 PETSC_EXTERN PetscErrorCode PetscCDFGaussian1D(const PetscReal[], const PetscReal[], PetscReal[]);
554 PETSC_EXTERN PetscErrorCode PetscPDFSampleGaussian1D(const PetscReal[], const PetscReal[], PetscReal[]);
555 PETSC_EXTERN PetscErrorCode PetscPDFGaussian2D(const PetscReal[], const PetscReal[], PetscReal[]);
556 PETSC_EXTERN PetscErrorCode PetscPDFSampleGaussian2D(const PetscReal[], const PetscReal[], PetscReal[]);
557 PETSC_EXTERN PetscErrorCode PetscPDFGaussian3D(const PetscReal[], const PetscReal[], PetscReal[]);
558 PETSC_EXTERN PetscErrorCode PetscPDFSampleGaussian3D(const PetscReal[], const PetscReal[], PetscReal[]);
559 PETSC_EXTERN PetscErrorCode PetscPDFConstant1D(const PetscReal[], const PetscReal[], PetscReal[]);
560 PETSC_EXTERN PetscErrorCode PetscCDFConstant1D(const PetscReal[], const PetscReal[], PetscReal[]);
561 PETSC_EXTERN PetscErrorCode PetscPDFSampleConstant1D(const PetscReal[], const PetscReal[], PetscReal[]);
562 PETSC_EXTERN PetscErrorCode PetscPDFConstant2D(const PetscReal[], const PetscReal[], PetscReal[]);
563 PETSC_EXTERN PetscErrorCode PetscCDFConstant2D(const PetscReal[], const PetscReal[], PetscReal[]);
564 PETSC_EXTERN PetscErrorCode PetscPDFSampleConstant2D(const PetscReal[], const PetscReal[], PetscReal[]);
565 PETSC_EXTERN PetscErrorCode PetscPDFConstant3D(const PetscReal[], const PetscReal[], PetscReal[]);
566 PETSC_EXTERN PetscErrorCode PetscCDFConstant3D(const PetscReal[], const PetscReal[], PetscReal[]);
567 PETSC_EXTERN PetscErrorCode PetscPDFSampleConstant3D(const PetscReal[], const PetscReal[], PetscReal[]);
568 PETSC_EXTERN PetscErrorCode PetscProbCreateFromOptions(PetscInt, const char[], const char[], PetscProbFunc *, PetscProbFunc *, PetscProbFunc *);
569 
570 #include <petscvec.h>
571 
572 PETSC_EXTERN PetscErrorCode PetscProbComputeKSStatistic(Vec, PetscProbFunc, PetscReal *);
573 
574 #endif
575