evalue_split_periods: gracefully handle zero evalues and inappropriate evalues
[barvinok.git] / bernstein.cc
blobda4a3e4e3b047a702ede799e59720b7d420ac5da
1 #include <vector>
2 #include <bernstein/bernstein.h>
3 #include <bernstein/piecewise_lst.h>
4 #include <barvinok/barvinok.h>
5 #include <barvinok/util.h>
6 #include <barvinok/bernstein.h>
7 #include <barvinok/options.h>
9 using namespace GiNaC;
10 using namespace bernstein;
12 using std::pair;
13 using std::vector;
14 using std::cerr;
15 using std::endl;
17 namespace barvinok {
19 ex evalue2ex(evalue *e, const exvector& vars)
21 if (value_notzero_p(e->d))
22 return value2numeric(e->x.n)/value2numeric(e->d);
23 if (e->x.p->type != polynomial)
24 return fail();
25 ex poly = 0;
26 for (int i = e->x.p->size-1; i >= 0; --i) {
27 poly *= vars[e->x.p->pos-1];
28 ex t = evalue2ex(&e->x.p->arr[i], vars);
29 if (is_exactly_a<fail>(t))
30 return t;
31 poly += t;
33 return poly;
36 static int type_offset(enode *p)
38 return p->type == fractional ? 1 :
39 p->type == flooring ? 1 : 0;
42 typedef pair<bool, const evalue *> typed_evalue;
44 static ex evalue2ex_add_var(evalue *e, exvector& extravar,
45 vector<typed_evalue>& expr, bool is_fract)
47 ex base_var = 0;
49 for (int i = 0; i < expr.size(); ++i) {
50 if (is_fract == expr[i].first && eequal(e, expr[i].second)) {
51 base_var = extravar[i];
52 break;
55 if (base_var != 0)
56 return base_var;
58 char name[20];
59 snprintf(name, sizeof(name), "f%c%d", is_fract ? 'r' : 'l', expr.size());
60 extravar.push_back(base_var = symbol(name));
61 expr.push_back(typed_evalue(is_fract, e));
63 return base_var;
66 /* For the argument e=(f/d) of a fractional, return (d-1)/d times
67 * a variable in [0,1] (see setup_constraints).
69 static ex evalue2ex_get_fract(evalue *e, exvector& extravar,
70 vector<typed_evalue>& expr)
72 ex f;
73 Value d;
74 ex den;
75 value_init(d);
76 value_set_si(d, 1);
77 evalue_denom(e, &d);
78 den = value2numeric(d);
79 value_clear(d);
80 f = (den-1)/den;
82 ex base_var = evalue2ex_add_var(e, extravar, expr, true);
83 base_var *= f;
84 return base_var;
87 static ex evalue2ex_r(const evalue *e, const exvector& vars,
88 exvector& extravar, vector<typed_evalue>& expr,
89 Vector *coset)
91 if (value_notzero_p(e->d))
92 return value2numeric(e->x.n)/value2numeric(e->d);
93 ex base_var = 0;
94 ex poly = 0;
96 switch (e->x.p->type) {
97 case polynomial:
98 base_var = vars[e->x.p->pos-1];
99 break;
100 case flooring:
101 base_var = evalue2ex_add_var(&e->x.p->arr[0], extravar, expr, false);
102 break;
103 case fractional:
104 base_var = evalue2ex_get_fract(&e->x.p->arr[0], extravar, expr);
105 break;
106 case periodic:
107 assert(coset);
108 return evalue2ex_r(&e->x.p->arr[VALUE_TO_INT(coset->p[e->x.p->pos-1])],
109 vars, extravar, expr, coset);
110 default:
111 return fail();
114 int offset = type_offset(e->x.p);
115 for (int i = e->x.p->size-1; i >= offset; --i) {
116 poly *= base_var;
117 ex t = evalue2ex_r(&e->x.p->arr[i], vars, extravar, expr, coset);
118 if (is_exactly_a<fail>(t))
119 return t;
120 poly += t;
122 return poly;
125 /* For each t = floor(e/d), set up two constraints
127 * e - d t >= 0
128 * -e + d t + d-1 >= 0
130 * e is assumed to be an affine expression.
132 * For each t = fract(e/d), set up two constraints
134 * -d t + d-1 >= 0
135 * t >= 0
137 static Matrix *setup_constraints(const vector<typed_evalue> expr, int nvar)
139 int extra = expr.size();
140 if (!extra)
141 return NULL;
142 Matrix *M = Matrix_Alloc(2*extra, 1+extra+nvar+1);
143 for (int i = 0; i < extra; ++i) {
144 if (expr[i].first) {
145 value_set_si(M->p[2*i][0], 1);
146 value_set_si(M->p[2*i][1+i], -1);
147 value_set_si(M->p[2*i][1+extra+nvar], 1);
148 value_set_si(M->p[2*i+1][0], 1);
149 value_set_si(M->p[2*i+1][1+i], 1);
150 } else {
151 Value *d = &M->p[2*i][1+i];
152 evalue_extract_affine(expr[i].second, M->p[2*i]+1+extra,
153 M->p[2*i]+1+extra+nvar, d);
154 value_oppose(*d, *d);
155 value_set_si(M->p[2*i][0], -1);
156 Vector_Scale(M->p[2*i], M->p[2*i+1], M->p[2*i][0], 1+extra+nvar+1);
157 value_set_si(M->p[2*i][0], 1);
158 value_subtract(M->p[2*i+1][1+extra+nvar], M->p[2*i+1][1+extra+nvar], *d);
159 value_decrement(M->p[2*i+1][1+extra+nvar], M->p[2*i+1][1+extra+nvar]);
162 return M;
165 static bool evalue_is_periodic(const evalue *e, Vector *periods)
167 int i, offset;
168 bool is_periodic = false;
170 if (value_notzero_p(e->d))
171 return false;
173 assert(e->x.p->type != partition);
174 if (e->x.p->type == periodic) {
175 Value size;
176 value_init(size);
177 value_set_si(size, e->x.p->size);
178 value_lcm(periods->p[e->x.p->pos-1], size, &periods->p[e->x.p->pos-1]);
179 value_clear(size);
180 is_periodic = true;
182 offset = type_offset(e->x.p);
183 for (i = e->x.p->size-1; i >= offset; --i)
184 is_periodic = evalue_is_periodic(&e->x.p->arr[i], periods) || is_periodic;
185 return is_periodic;
188 static ex evalue2lst(const evalue *e, const exvector& vars,
189 exvector& extravar, vector<typed_evalue>& expr,
190 Vector *periods)
192 Vector *coset = Vector_Alloc(periods->Size);
193 lst list;
194 for (;;) {
195 int i;
196 list.append(evalue2ex_r(e, vars, extravar, expr, coset));
197 for (i = coset->Size-1; i >= 0; --i) {
198 value_increment(coset->p[i], coset->p[i]);
199 if (value_lt(coset->p[i], periods->p[i]))
200 break;
201 value_set_si(coset->p[i], 0);
203 if (i < 0)
204 break;
206 Vector_Free(coset);
207 return list;
210 ex evalue2ex(const evalue *e, const exvector& vars, exvector& floorvar,
211 Matrix **C, Vector **p)
213 vector<typed_evalue> expr;
214 Vector *periods = Vector_Alloc(vars.size());
215 assert(p);
216 assert(C);
217 for (int i = 0; i < periods->Size; ++i)
218 value_set_si(periods->p[i], 1);
219 if (evalue_is_periodic(e, periods)) {
220 *p = periods;
221 *C = NULL;
222 lst list;
223 return list;
224 } else {
225 Vector_Free(periods);
226 *p = NULL;
227 ex poly = evalue2ex_r(e, vars, floorvar, expr, NULL);
228 Matrix *M = setup_constraints(expr, vars.size());
229 *C = M;
230 return poly;
234 /* if the evalue is a relation, we use the relation to cut off the
235 * the edges of the domain
237 static void evalue_extract_poly(evalue *e, int i, Polyhedron **D, evalue **poly,
238 unsigned MaxRays)
240 *D = EVALUE_DOMAIN(e->x.p->arr[2*i]);
241 *poly = e = &e->x.p->arr[2*i+1];
242 if (value_notzero_p(e->d))
243 return;
244 if (e->x.p->type != relation)
245 return;
246 if (e->x.p->size > 2)
247 return;
248 evalue *fr = &e->x.p->arr[0];
249 assert(value_zero_p(fr->d));
250 assert(fr->x.p->type == fractional);
251 assert(fr->x.p->size == 3);
252 Matrix *T = Matrix_Alloc(2, (*D)->Dimension+1);
253 value_set_si(T->p[1][(*D)->Dimension], 1);
255 /* convert argument of fractional to polylib */
256 /* the argument is assumed to be linear */
257 evalue *p = &fr->x.p->arr[0];
258 evalue_denom(p, &T->p[1][(*D)->Dimension]);
259 for (;value_zero_p(p->d); p = &p->x.p->arr[0]) {
260 assert(p->x.p->type == polynomial);
261 assert(p->x.p->size == 2);
262 assert(value_notzero_p(p->x.p->arr[1].d));
263 int pos = p->x.p->pos - 1;
264 value_assign(T->p[0][pos], p->x.p->arr[1].x.n);
265 value_multiply(T->p[0][pos], T->p[0][pos], T->p[1][(*D)->Dimension]);
266 value_division(T->p[0][pos], T->p[0][pos], p->x.p->arr[1].d);
268 int pos = (*D)->Dimension;
269 value_assign(T->p[0][pos], p->x.n);
270 value_multiply(T->p[0][pos], T->p[0][pos], T->p[1][(*D)->Dimension]);
271 value_division(T->p[0][pos], T->p[0][pos], p->d);
273 Polyhedron *E = NULL;
274 for (Polyhedron *P = *D; P; P = P->next) {
275 Polyhedron *I = Polyhedron_Image(P, T, MaxRays);
276 I = DomainConstraintSimplify(I, MaxRays);
277 Polyhedron *R = Polyhedron_Preimage(I, T, MaxRays);
278 Polyhedron_Free(I);
279 Polyhedron *next = P->next;
280 P->next = NULL;
281 Polyhedron *S = DomainIntersection(P, R, MaxRays);
282 Polyhedron_Free(R);
283 P->next = next;
284 if (emptyQ2(S))
285 Polyhedron_Free(S);
286 else
287 E = DomainConcat(S, E);
289 Matrix_Free(T);
291 *D = E;
292 *poly = &e->x.p->arr[1];
295 piecewise_lst *evalue_bernstein_coefficients(piecewise_lst *pl_all, evalue *e,
296 Polyhedron *ctx, const exvector& params)
298 piecewise_lst *pl;
299 barvinok_options *options = barvinok_options_new_with_defaults();
300 pl = evalue_bernstein_coefficients(pl_all, e, ctx, params, options);
301 barvinok_options_free(options);
302 return pl;
305 static piecewise_lst *bernstein_coefficients(piecewise_lst *pl_all,
306 Polyhedron *D, const ex& poly,
307 Polyhedron *ctx,
308 const exvector& params, const exvector& floorvar,
309 barvinok_options *options);
311 static piecewise_lst *bernstein_coefficients_product(piecewise_lst *pl_all,
312 Polyhedron *F, Matrix *T, const ex& poly,
313 Polyhedron *ctx,
314 const exvector& params, const exvector& vars,
315 barvinok_options *options)
317 if (emptyQ2(ctx))
318 return pl_all;
319 for (Polyhedron *G = F; G; G = G->next)
320 if (emptyQ2(G))
321 return pl_all;
323 unsigned nparam = params.size();
324 unsigned nvar = vars.size();
325 unsigned constraints;
326 Polyhedron *C = NULL;
328 /* More context constraints */
329 if (F->Dimension == ctx->Dimension) {
330 C = F;
331 F = F->next;
333 assert(F);
334 assert(F->next);
336 Matrix *M;
337 Polyhedron *P;
338 Polyhedron *PC;
339 M = Matrix_Alloc(F->NbConstraints, 1+nvar+nparam+1);
340 for (int i = 0; i < F->NbConstraints; ++i) {
341 Vector_Copy(F->Constraint[i], M->p[i], 1+F->Dimension-nparam);
342 Vector_Copy(F->Constraint[i]+1+F->Dimension-nparam,
343 M->p[i]+1+nvar, nparam+1);
345 P = Constraints2Polyhedron(M, options->MaxRays);
346 Matrix_Free(M);
348 constraints = C ? C->NbConstraints : 0;
349 constraints += ctx->NbConstraints;
350 for (Polyhedron *G = F->next; G; G = G->next)
351 constraints += G->NbConstraints;
353 unsigned total_var = nvar-(F->Dimension-nparam);
354 unsigned skip = 0;
355 unsigned c = 0;
356 M = Matrix_Alloc(constraints, 1+total_var+nparam+1);
357 for (Polyhedron *G = F->next; G; G = G->next) {
358 unsigned this_var = G->Dimension - nparam;
359 for (int i = 0; i < G->NbConstraints; ++i) {
360 value_assign(M->p[c+i][0], G->Constraint[i][0]);
361 Vector_Copy(G->Constraint[i]+1, M->p[c+i]+1+skip, this_var);
362 Vector_Copy(G->Constraint[i]+1+this_var, M->p[c+i]+1+total_var,
363 nparam+1);
365 c += G->NbConstraints;
366 skip += this_var;
368 assert(skip == total_var);
369 if (C) {
370 for (int i = 0; i < C->NbConstraints; ++i) {
371 value_assign(M->p[c+i][0], C->Constraint[i][0]);
372 Vector_Copy(C->Constraint[i]+1, M->p[c+i]+1+total_var,
373 nparam+1);
375 c += C->NbConstraints;
377 for (int i = 0; i < ctx->NbConstraints; ++i) {
378 value_assign(M->p[c+i][0], ctx->Constraint[i][0]);
379 Vector_Copy(ctx->Constraint[i]+1, M->p[c+i]+1+total_var, nparam+1);
381 PC = Constraints2Polyhedron(M, options->MaxRays);
382 Matrix_Free(M);
384 exvector newvars = constructVariableVector(nvar, "t");
385 matrix subs(1, nvar);
386 for (int i = 0; i < nvar; ++i)
387 for (int j = 0; j < nvar; ++j)
388 subs(0,i) += value2numeric(T->p[i][j]) * newvars[j];
390 ex newpoly = replaceVariablesInPolynomial(poly, vars, subs);
392 exvector P_vars;
393 P_vars.insert(P_vars.end(), newvars.begin(),
394 newvars.begin()+(F->Dimension-nparam));
395 exvector P_params;
396 P_params.insert(P_params.end(), newvars.begin()+(F->Dimension-nparam),
397 newvars.end());
398 P_params.insert(P_params.end(), params.begin(), params.end());
399 piecewise_lst *pl;
400 pl = bernstein_coefficients(NULL, P, newpoly, PC, P_params, P_vars, options);
401 Polyhedron_Free(P);
402 Polyhedron_Free(PC);
404 if (options->bernstein_optimize == BV_BERNSTEIN_MIN)
405 pl->minimize();
406 else if (options->bernstein_optimize == BV_BERNSTEIN_MAX)
407 pl->maximize();
409 unsigned done = F->Dimension-nparam;
410 for (F = F->next ; F; F = F->next) {
411 exvector pl_vars;
412 pl_vars.insert(pl_vars.end(), newvars.begin()+done,
413 newvars.begin()+done+(F->Dimension-nparam));
414 exvector pl_params;
415 pl_params.insert(pl_params.end(), newvars.begin()+done+(F->Dimension-nparam),
416 newvars.end());
417 pl_params.insert(pl_params.end(), params.begin(), params.end());
418 piecewise_lst *new_pl = NULL;
419 Polyhedron *U = Universe_Polyhedron(pl_params.size());
421 for (int i = 0; i < pl->list.size(); ++i) {
422 Polyhedron *D = pl->list[i].first;
423 lst polys = pl->list[i].second;
424 new_pl = bernstein_coefficients(new_pl, D, polys, U, pl_params,
425 pl_vars, options);
428 delete pl;
429 pl = new_pl;
431 if (options->bernstein_optimize == BV_BERNSTEIN_MIN)
432 pl->minimize();
433 else if (options->bernstein_optimize == BV_BERNSTEIN_MAX)
434 pl->maximize();
436 Polyhedron_Free(U);
437 done += F->Dimension-nparam;
440 if (!pl_all)
441 pl_all = pl;
442 else {
443 pl_all->combine(*pl);
444 delete pl;
447 return pl_all;
450 static piecewise_lst *bernstein_coefficients_polyhedron(piecewise_lst *pl_all,
451 Polyhedron *P, const ex& poly,
452 Polyhedron *ctx,
453 const exvector& params, const exvector& floorvar,
454 barvinok_options *options)
456 if (Polyhedron_is_unbounded(P, ctx->Dimension, options->MaxRays)) {
457 fprintf(stderr, "warning: unbounded domain skipped\n");
458 Polyhedron_Print(stderr, P_VALUE_FMT, P);
459 return pl_all;
462 Matrix *T = NULL;
463 Polyhedron *F = Polyhedron_Factor(P, ctx->Dimension, &T, options->MaxRays);
464 if (F) {
465 pl_all = bernstein_coefficients_product(pl_all, F, T, poly, ctx, params,
466 floorvar, options);
467 Domain_Free(F);
468 Matrix_Free(T);
469 return pl_all;
472 unsigned PP_MaxRays = options->MaxRays;
473 if (PP_MaxRays & POL_NO_DUAL)
474 PP_MaxRays = 0;
476 Param_Polyhedron *PP = Polyhedron2Param_Domain(P, ctx, PP_MaxRays);
477 assert(PP);
478 piecewise_lst *pl = new piecewise_lst(params);
479 for (Param_Domain *Q = PP->D; Q; Q = Q->next) {
480 matrix VM = domainVertices(PP, Q, params);
481 lst coeffs = bernsteinExpansion(VM, poly, floorvar, params);
482 pl->list.push_back(guarded_lst(Polyhedron_Copy(Q->Domain), coeffs));
484 Param_Polyhedron_Free(PP);
485 if (!pl_all)
486 pl_all = pl;
487 else {
488 pl_all->combine(*pl);
489 delete pl;
492 return pl_all;
495 static piecewise_lst *bernstein_coefficients(piecewise_lst *pl_all,
496 Polyhedron *D, const ex& poly,
497 Polyhedron *ctx,
498 const exvector& params, const exvector& floorvar,
499 barvinok_options *options)
501 if (!D->next && emptyQ2(D))
502 return pl_all;
504 for (Polyhedron *P = D; P; P = P->next) {
505 /* This shouldn't happen */
506 if (emptyQ2(P))
507 continue;
508 Polyhedron *next = P->next;
509 P->next = NULL;
510 pl_all = bernstein_coefficients_polyhedron(pl_all, P, poly, ctx,
511 params, floorvar, options);
512 P->next = next;
514 return pl_all;
517 /* Compute the coefficients of the polynomial corresponding to each coset
518 * on its own domain. This allows us to cut the domain on multiples of
519 * the period.
520 * To perform the cutting for a coset "i mod n = c" we map the domain
521 * to the quotient space trough "i = i' n + c", simplify the constraints
522 * (implicitly) and then map back to the original space.
524 static piecewise_lst *bernstein_coefficients_periodic(piecewise_lst *pl_all,
525 Polyhedron *D, const evalue *e,
526 Polyhedron *ctx, const exvector& vars,
527 const exvector& params, Vector *periods,
528 barvinok_options *options)
530 assert(D->Dimension == periods->Size);
531 Matrix *T = Matrix_Alloc(D->Dimension+1, D->Dimension+1);
532 Matrix *T2 = Matrix_Alloc(D->Dimension+1, D->Dimension+1);
533 Vector *coset = Vector_Alloc(periods->Size);
534 exvector extravar;
535 vector<typed_evalue> expr;
536 exvector allvars = vars;
537 allvars.insert(allvars.end(), params.begin(), params.end());
539 value_set_si(T2->p[D->Dimension][D->Dimension], 1);
540 for (int i = 0; i < D->Dimension; ++i) {
541 value_assign(T->p[i][i], periods->p[i]);
542 value_lcm(T2->p[D->Dimension][D->Dimension], periods->p[i],
543 &T2->p[D->Dimension][D->Dimension]);
545 value_set_si(T->p[D->Dimension][D->Dimension], 1);
546 for (int i = 0; i < D->Dimension; ++i)
547 value_division(T2->p[i][i], T2->p[D->Dimension][D->Dimension],
548 periods->p[i]);
549 for (;;) {
550 int i;
551 ex poly = evalue2ex_r(e, allvars, extravar, expr, coset);
552 assert(extravar.size() == 0);
553 assert(expr.size() == 0);
554 Polyhedron *E = DomainPreimage(D, T, options->MaxRays);
555 Polyhedron *F = DomainPreimage(E, T2, options->MaxRays);
556 Polyhedron_Free(E);
557 if (!emptyQ2(F))
558 pl_all = bernstein_coefficients(pl_all, F, poly, ctx, params,
559 vars, options);
560 Polyhedron_Free(F);
561 for (i = D->Dimension-1; i >= 0; --i) {
562 value_increment(coset->p[i], coset->p[i]);
563 value_increment(T->p[i][D->Dimension], T->p[i][D->Dimension]);
564 value_subtract(T2->p[i][D->Dimension], T2->p[i][D->Dimension],
565 T2->p[i][i]);
566 if (value_lt(coset->p[i], periods->p[i]))
567 break;
568 value_set_si(coset->p[i], 0);
569 value_set_si(T->p[i][D->Dimension], 0);
570 value_set_si(T2->p[i][D->Dimension], 0);
572 if (i < 0)
573 break;
575 Vector_Free(coset);
576 Matrix_Free(T);
577 Matrix_Free(T2);
578 return pl_all;
581 piecewise_lst *evalue_bernstein_coefficients(piecewise_lst *pl_all, evalue *e,
582 Polyhedron *ctx, const exvector& params,
583 barvinok_options *options)
585 unsigned nparam = ctx->Dimension;
586 if (EVALUE_IS_ZERO(*e))
587 return pl_all;
588 assert(value_zero_p(e->d));
589 assert(e->x.p->type == partition);
590 assert(e->x.p->size >= 2);
591 unsigned nvars = EVALUE_DOMAIN(e->x.p->arr[0])->Dimension - nparam;
593 exvector vars = constructVariableVector(nvars, "v");
594 exvector allvars = vars;
595 allvars.insert(allvars.end(), params.begin(), params.end());
597 for (int i = 0; i < e->x.p->size/2; ++i) {
598 Polyhedron *E;
599 evalue *EP;
600 Matrix *M;
601 Vector *periods;
602 exvector floorvar;
604 evalue_extract_poly(e, i, &E, &EP, options->MaxRays);
605 ex poly = evalue2ex(EP, allvars, floorvar, &M, &periods);
606 floorvar.insert(floorvar.end(), vars.begin(), vars.end());
607 if (M) {
608 Polyhedron *AE = align_context(E, M->NbColumns-2, options->MaxRays);
609 if (E != EVALUE_DOMAIN(e->x.p->arr[2*i]))
610 Domain_Free(E);
611 E = DomainAddConstraints(AE, M, options->MaxRays);
612 Matrix_Free(M);
613 Domain_Free(AE);
615 if (is_exactly_a<fail>(poly)) {
616 if (E != EVALUE_DOMAIN(e->x.p->arr[2*i]))
617 Domain_Free(E);
618 delete pl_all;
619 return NULL;
621 if (periods)
622 pl_all = bernstein_coefficients_periodic(pl_all, E, EP, ctx, vars,
623 params, periods, options);
624 else
625 pl_all = bernstein_coefficients(pl_all, E, poly, ctx, params,
626 floorvar, options);
627 if (periods)
628 Vector_Free(periods);
629 if (E != EVALUE_DOMAIN(e->x.p->arr[2*i]))
630 Domain_Free(E);
632 return pl_all;