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1 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
2 /*
3  * Main authors:
4  * Christian Schulte <schulte@gecode.org>
5  * Vincent Barichard <Vincent.Barichard@univ-angers.fr>
6  *
7  * Copyright:
8  * Christian Schulte, 2003
9  * Vincent Barichard, 2012
10  *
11  * Last modified:
12  * $Date: 2013-02-13 16:01:33 +0100 (Wed, 13 Feb 2013) $ by $Author: vbarichard $
13  * $Revision: 13289 $
14  *
15  * This file is part of Gecode, the generic constraint
16  * development environment:
17  * http://www.gecode.org
18  *
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24  * permit persons to whom the Software is furnished to do so, subject to
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37  *
38  */
39 
40 namespace Gecode { namespace Float { namespace Linear {
41 
42  /*
43  * Linear propagators
44  *
45  */
46  template<class P, class N, PropCond pc>
49  : Propagator(home), x(x0), y(y0), c(c0) {
50  x.subscribe(home,*this,pc);
51  y.subscribe(home,*this,pc);
52  }
53 
54  template<class P, class N, PropCond pc>
56  Lin<P,N,pc>::Lin(Space& home, bool share, Lin<P,N,pc>& p)
57  : Propagator(home,share,p), c(p.c) {
58  x.update(home,share,p.x);
59  y.update(home,share,p.y);
60  }
61 
62  template<class P, class N, PropCond pc>
63  PropCost
64  Lin<P,N,pc>::cost(const Space&, const ModEventDelta&) const {
65  return PropCost::linear(PropCost::LO, x.size()+y.size());
66  }
67 
68  template<class P, class N, PropCond pc>
69  forceinline size_t
71  x.cancel(home,*this,pc);
72  y.cancel(home,*this,pc);
73  (void) Propagator::dispose(home);
74  return sizeof(*this);
75  }
76 
77 
78  /*
79  * Computing bounds
80  *
81  */
82 // template<class View>
83 // void
84 // bounds_p(Rounding& r, ModEventDelta med, ViewArray<View>& x, FloatVal& c, FloatNum& sl, FloatNum& su) {
85 // int n = x.size();
86 // if (FloatView::me(med) == ME_FLOAT_VAL) {
87 // for (int i = n; i--; ) {
88 // if (x[i].assigned()) {
89 // c -= x[i].val(); x[i] = x[--n];
90 // } else {
91 // sl = r.sub_up(sl,x[i].min()); su = r.sub_down(su,x[i].max());
92 // }
93 // }
94 // x.size(n);
95 // } else {
96 // for (int i = n; i--; ) {
97 // sl = r.sub_up(sl,x[i].min()); su = r.sub_down(su,x[i].max());
98 // }
99 // }
100 // }
101 //
102 // template<class View>
103 // void
104 // bounds_n(Rounding& r, ModEventDelta med, ViewArray<View>& y, FloatVal& c, FloatNum& sl, FloatNum& su) {
105 // int n = y.size();
106 // if (FloatView::me(med) == ME_FLOAT_VAL) {
107 // for (int i = n; i--; ) {
108 // if (y[i].assigned()) {
109 // c += y[i].val(); y[i] = y[--n];
110 // } else {
111 // sl = r.add_up(sl,y[i].max()); su = r.add_down(su,y[i].min());
112 // }
113 // }
114 // y.size(n);
115 // } else {
116 // for (int i = n; i--; ) {
117 // sl = r.add_up(sl,y[i].max()); su = r.add_down(su,y[i].min());
118 // }
119 // }
120 // }
121 
122  template<class View>
123  void
125  int n = x.size();
126 
127  if (FloatView::me(med) == ME_FLOAT_VAL) {
128  for (int i = n; i--; ) {
129  if (x[i].assigned()) {
130  c -= x[i].val(); x[i] = x[--n];
131  }
132  }
133  x.size(n);
134  }
135  }
136 
137  template<class View>
138  void
140  int n = y.size();
141  if (FloatView::me(med) == ME_FLOAT_VAL) {
142  for (int i = n; i--; ) {
143  if (y[i].assigned()) {
144  c += y[i].val(); y[i] = y[--n];
145  }
146  }
147  y.size(n);
148  }
149  }
150 
151  forceinline bool
152  infty(const FloatNum& n) {
153  return ((n == std::numeric_limits<FloatNum>::infinity()) ||
155  }
156 
157  /*
158  * Bound consistent linear equation
159  *
160  */
161 
162  template<class P, class N>
165  : Lin<P,N,PC_FLOAT_BND>(home,x,y,c) {}
166 
167  template<class P, class N>
168  ExecStatus
170  (void) new (home) Eq<P,N>(home,x,y,c);
171  return ES_OK;
172  }
173 
174 
175  template<class P, class N>
177  Eq<P,N>::Eq(Space& home, bool share, Eq<P,N>& p)
178  : Lin<P,N,PC_FLOAT_BND>(home,share,p) {}
179 
180  template<class P, class N>
181  Actor*
182  Eq<P,N>::copy(Space& home, bool share) {
183  return new (home) Eq<P,N>(home,share,*this);
184  }
185 
186  template<class P, class N>
187  ExecStatus
189  // Eliminate singletons
190  Rounding r;
191  eliminate_p<P>(med, x, c);
192  eliminate_n<N>(med, y, c);
193 
194  if ((FloatView::me(med) == ME_FLOAT_VAL) && ((x.size() + y.size()) <= 1)) {
195  if (x.size() == 1) {
196  GECODE_ME_CHECK(x[0].eq(home,c));
197  return home.ES_SUBSUMED(*this);
198  }
199  if (y.size() == 1) {
200  GECODE_ME_CHECK(y[0].eq(home,-c));
201  return home.ES_SUBSUMED(*this);
202  }
203  return (c.in(0.0)) ? home.ES_SUBSUMED(*this) : ES_FAILED;
204  }
205 
206  ExecStatus es = ES_FIX;
207  bool assigned = true;
208 
209  // Propagate max bound for positive variables
210  for (int i = x.size(); i--; ) {
211  // Compute bound
212  FloatNum sl = c.max();
213  for (int j = x.size(); j--; ) {
214  if (i == j) continue;
215  sl = r.sub_up(sl,x[j].min());
216  }
217  for (int j = y.size(); j--; )
218  sl = r.add_up(sl,y[j].max());
219  ModEvent me = x[i].lq(home,sl);
220  if (me_failed(me))
221  return ES_FAILED;
222  if (me != ME_FLOAT_VAL)
223  assigned = false;
224  if (me_modified(me))
225  es = ES_NOFIX;
226  }
227  // Propagate min bound for negative variables
228  for (int i = y.size(); i--; ) {
229  // Compute bound
230  FloatNum sl = -c.max();
231  for (int j = x.size(); j--; )
232  sl = r.add_down(sl,x[j].min());
233  for (int j = y.size(); j--; ) {
234  if (i == j) continue;
235  sl = r.sub_down(sl,y[j].max());
236  }
237  ModEvent me = y[i].gq(home,sl);
238  if (me_failed(me))
239  return ES_FAILED;
240  if (me != ME_FLOAT_VAL)
241  assigned = false;
242  if (me_modified(me))
243  es = ES_NOFIX;
244  }
245 
246  // Propagate min bound for positive variables
247  for (int i = x.size(); i--; ) {
248  // Compute bound
249  FloatNum su = c.min();
250  for (int j = x.size(); j--; ) {
251  if (i == j) continue;
252  su = r.sub_down(su,x[j].max());
253  }
254  for (int j = y.size(); j--; )
255  su = r.add_down(su,y[j].min());
256  ModEvent me = x[i].gq(home,su);
257  if (me_failed(me))
258  return ES_FAILED;
259  if (me != ME_FLOAT_VAL)
260  assigned = false;
261  if (me_modified(me))
262  es = ES_NOFIX;
263  }
264  // Propagate max bound for negative variables
265  for (int i = y.size(); i--; ) {
266  // Compute bound
267  FloatNum su = -c.min();
268  for (int j = x.size(); j--; )
269  su = r.add_up(su,x[j].max());
270  for (int j = y.size(); j--; ) {
271  if (i == j) continue;
272  su = r.sub_up(su,y[j].min());
273  }
274  ModEvent me = y[i].lq(home,su);
275  if (me_failed(me))
276  return ES_FAILED;
277  if (me != ME_FLOAT_VAL)
278  assigned = false;
279  if (me_modified(me))
280  es = ES_NOFIX;
281  }
282 
283  return assigned ? home.ES_SUBSUMED(*this) : es;
284  }
285 
286 
287  /*
288  * Bound consistent linear inequation
289  *
290  */
291 
292  template<class P, class N>
295  : Lin<P,N,PC_FLOAT_BND>(home,x,y,c) {}
296 
297  template<class P, class N>
298  ExecStatus
300  (void) new (home) Lq<P,N>(home,x,y,c);
301  return ES_OK;
302  }
303 
304  template<class P, class N>
306  Lq<P,N>::Lq(Space& home, bool share, Lq<P,N>& p)
307  : Lin<P,N,PC_FLOAT_BND>(home,share,p) {}
308 
309  template<class P, class N>
310  Actor*
311  Lq<P,N>::copy(Space& home, bool share) {
312  return new (home) Lq<P,N>(home,share,*this);
313  }
314 
315  template<class P, class N>
316  ExecStatus
318  // Eliminate singletons
319  FloatNum sl = 0.0;
320 
321  Rounding r;
322 
323  if (FloatView::me(med) == ME_FLOAT_VAL) {
324  for (int i = x.size(); i--; ) {
325  if (x[i].assigned()) {
326  c -= x[i].val(); x.move_lst(i);
327  } else {
328  sl = r.sub_up(sl,x[i].min());
329  }
330  }
331  for (int i = y.size(); i--; ) {
332  if (y[i].assigned()) {
333  c += y[i].val(); y.move_lst(i);
334  } else {
335  sl = r.add_up(sl,y[i].max());
336  }
337  }
338  if ((x.size() + y.size()) <= 1) {
339  if (x.size() == 1) {
340  GECODE_ME_CHECK(x[0].lq(home,c.max()));
341  return home.ES_SUBSUMED(*this);
342  }
343  if (y.size() == 1) {
344  GECODE_ME_CHECK(y[0].gq(home,(-c).min()));
345  return home.ES_SUBSUMED(*this);
346  }
347  return (c.max() >= 0) ? home.ES_SUBSUMED(*this) : ES_FAILED;
348  }
349  } else {
350  for (int i = x.size(); i--; )
351  sl = r.sub_up(sl,x[i].min());
352  for (int i = y.size(); i--; )
353  sl = r.add_up(sl,y[i].max());
354  }
355 
356  sl = r.add_up(sl,c.max());
357 
358  ExecStatus es = ES_FIX;
359  bool assigned = true;
360  for (int i = x.size(); i--; ) {
361  assert(!x[i].assigned());
362  FloatNum slx = r.add_up(sl,x[i].min());
363  ModEvent me = x[i].lq(home,slx);
364  if (me == ME_FLOAT_FAILED)
365  return ES_FAILED;
366  if (me != ME_FLOAT_VAL)
367  assigned = false;
368  if (me_modified(me))
369  es = ES_NOFIX;
370  }
371 
372  for (int i = y.size(); i--; ) {
373  assert(!y[i].assigned());
374  FloatNum sly = r.sub_up(y[i].max(),sl);
375  ModEvent me = y[i].gq(home,sly);
376  if (me == ME_FLOAT_FAILED)
377  return ES_FAILED;
378  if (me != ME_FLOAT_VAL)
379  assigned = false;
380  if (me_modified(me))
381  es = ES_NOFIX;
382  }
383 
384  return assigned ? home.ES_SUBSUMED(*this) : es;
385  }
386 
387 }}}
388 
389 // STATISTICS: float-prop
390