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sqr-sqrt.hpp

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00001 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
00002 /*
00003  *  Main authors:
00004  *     Christian Schulte <schulte@gecode.org>
00005  *     Guido Tack <tack@gecode.org>
00006  *     Vincent Barichard <Vincent.Barichard@univ-angers.fr>
00007  *
00008  *  Copyright:
00009  *     Christian Schulte, 2004
00010  *     Guido Tack, 2006
00011  *     Vincent Barichard, 2012
00012  *
00013  *  This file is part of Gecode, the generic constraint
00014  *  development environment:
00015  *     http://www.gecode.org
00016  *
00017  *  Permission is hereby granted, free of charge, to any person obtaining
00018  *  a copy of this software and associated documentation files (the
00019  *  "Software"), to deal in the Software without restriction, including
00020  *  without limitation the rights to use, copy, modify, merge, publish,
00021  *  distribute, sublicense, and/or sell copies of the Software, and to
00022  *  permit persons to whom the Software is furnished to do so, subject to
00023  *  the following conditions:
00024  *
00025  *  The above copyright notice and this permission notice shall be
00026  *  included in all copies or substantial portions of the Software.
00027  *
00028  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00029  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00030  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00031  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
00032  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
00033  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
00034  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00035  *
00036  */
00037 
00038 namespace Gecode { namespace Float { namespace Arithmetic {
00039 
00040   /*
00041    * Positive bounds consistent squaring
00042    *
00043    */
00044   template<class VA, class VB>
00045   forceinline
00046   SqrPlus<VA,VB>::SqrPlus(Home home, VA x0, VB x1)
00047     : MixBinaryPropagator<VA,PC_FLOAT_BND,VB,PC_FLOAT_BND>(home,x0,x1) {}
00048 
00049   template<class VA, class VB>
00050   forceinline ExecStatus
00051   SqrPlus<VA,VB>::post(Home home, VA x0, VB x1) {
00052     if (x0 == x1) {
00053       if (x0.assigned())
00054         return ((x0.val() == 0) || (x0.val() == 1))? ES_OK : ES_FAILED;
00055     } else {
00056       GECODE_ME_CHECK(x0.eq(home,sqrt(x1.val())));
00057       GECODE_ME_CHECK(x1.eq(home,sqr(x0.val())));
00058     }
00059 
00060     (void) new (home) SqrPlus<VA,VB>(home,x0,x1);
00061     return ES_OK;
00062   }
00063 
00064   template<class VA, class VB>
00065   forceinline
00066   SqrPlus<VA,VB>::SqrPlus(Space& home, SqrPlus<VA,VB>& p)
00067     : MixBinaryPropagator<VA,PC_FLOAT_BND,VB,PC_FLOAT_BND>(home,p) {}
00068 
00069   template<class VA, class VB>
00070   Actor*
00071   SqrPlus<VA,VB>::copy(Space& home) {
00072     return new (home) SqrPlus<VA,VB>(home,*this);
00073   }
00074 
00075   template<class VA, class VB>
00076   ExecStatus
00077   SqrPlus<VA,VB>::propagate(Space& home, const ModEventDelta&) {
00078     if (x0 == x1) {
00079       if (x0.max() < 1) GECODE_ME_CHECK(x0.eq(home,0));
00080       else if (x0.min() > 0) GECODE_ME_CHECK(x0.eq(home,1));
00081       if (x0.assigned())
00082         return ((x0.val() == 0) || (x0.val() == 1))? home.ES_SUBSUMED(*this) : ES_FAILED;
00083     } else {
00084       GECODE_ME_CHECK(x0.eq(home,sqrt(x1.val())));
00085       GECODE_ME_CHECK(x1.eq(home,sqr(x0.val())));
00086       if (x0.assigned() || x1.assigned()) return home.ES_SUBSUMED(*this);
00087     }
00088 
00089     return ES_FIX;
00090   }
00091 
00092 
00093   /*
00094    * Bounds consistent squaring
00095    *
00096    */
00097 
00098   template<class View>
00099   forceinline
00100   Sqr<View>::Sqr(Home home, View x0, View x1)
00101     : BinaryPropagator<View,PC_FLOAT_BND>(home,x0,x1) {}
00102 
00103   template<class View>
00104   forceinline ExecStatus
00105   Sqr<View>::post(Home home, View x0, View x1) {
00106     GECODE_ME_CHECK(x1.gq(home,0));
00107     if (x0 == x1) {
00108       if (x0.assigned())
00109         return ((x0.val() == 0) || (x0.val() == 1))? ES_OK : ES_FAILED;
00110       GECODE_ME_CHECK(x1.lq(home,1));
00111       return SqrPlus<FloatView,FloatView>::post(home,x0,x1);
00112     } else {
00113       if (x0.min() >= 0)
00114         return SqrPlus<FloatView,FloatView>::post(home,x0,x1);
00115       if (x0.max() <= 0)
00116         return SqrPlus<MinusView,FloatView>::post(home,MinusView(x0),x1);
00117       GECODE_ME_CHECK(x1.eq(home,sqr(x0.val())));
00118       (void) new (home) Sqr<View>(home,x0,x1);
00119     }
00120     return ES_OK;
00121   }
00122 
00123   template<class View>
00124   forceinline
00125   Sqr<View>::Sqr(Space& home, Sqr<View>& p)
00126     : BinaryPropagator<View,PC_FLOAT_BND>(home,p) {}
00127 
00128   template<class View>
00129   Actor*
00130   Sqr<View>::copy(Space& home) {
00131     return new (home) Sqr<View>(home,*this);
00132   }
00133 
00134   template<class View>
00135   ExecStatus
00136   Sqr<View>::propagate(Space& home, const ModEventDelta&) {
00137     assert(x1.min() >= 0);
00138     if (x0.min() >= 0)
00139       GECODE_REWRITE(*this,(SqrPlus<FloatView,FloatView>::post(home(*this),x0,x1)));
00140     if (x0.max() <= 0)
00141       GECODE_REWRITE(*this,(SqrPlus<MinusView,FloatView>::post(home(*this),
00142         MinusView(x0),x1)));
00143 
00144     GECODE_ME_CHECK(x1.eq(home,sqr(x0.val())));
00145     Rounding r;
00146     FloatVal z = sqrt(x1.val());
00147     if (x0.min() > -r.sqrt_up(x1.min()))
00148       GECODE_ME_CHECK(x0.eq(home,z));
00149     else if (x0.max() < r.sqrt_down(x1.min()))
00150       GECODE_ME_CHECK(x0.eq(home,-z));
00151     else
00152       GECODE_ME_CHECK(x0.eq(home,hull(z,-z)));
00153 
00154     return ES_NOFIX;
00155   }
00156 
00157 
00158   /*
00159    * Bounds consistent square root operator
00160    *
00161    */
00162 
00163   template<class A, class B>
00164   forceinline
00165   Sqrt<A,B>::Sqrt(Home home, A x0, B x1)
00166     : MixBinaryPropagator<A,PC_FLOAT_BND,B,PC_FLOAT_BND>(home,x0,x1) {}
00167 
00168   template<class A, class B>
00169   ExecStatus
00170   Sqrt<A,B>::post(Home home, A x0, B x1) {
00171     GECODE_ME_CHECK(x0.gq(home,0));
00172     if (x0 == x1) {
00173       if (x0.assigned())
00174         return ((x0.val() == 0) || (x0.val() == 1))? ES_OK : ES_FAILED;
00175       GECODE_ME_CHECK(x0.lq(home,1));
00176       (void) new (home) Sqrt<A,B>(home,x0,x1);
00177     } else {
00178       GECODE_ME_CHECK(x1.eq(home,sqrt(x0.val())));
00179       (void) new (home) Sqrt<A,B>(home,x0,x1);
00180     }
00181     return ES_OK;
00182   }
00183 
00184   template<class A, class B>
00185   forceinline
00186   Sqrt<A,B>::Sqrt(Space& home, Sqrt<A,B>& p)
00187     : MixBinaryPropagator<A,PC_FLOAT_BND,B,PC_FLOAT_BND>(home,p) {}
00188 
00189   template<class A, class B>
00190   Actor*
00191   Sqrt<A,B>::copy(Space& home) {
00192     return new (home) Sqrt<A,B>(home,*this);
00193   }
00194 
00195   template<class A, class B>
00196   ExecStatus
00197   Sqrt<A,B>::propagate(Space& home, const ModEventDelta&) {
00198     if (x0 == x1) {
00199       if (x0.max() < 1) GECODE_ME_CHECK(x0.eq(home,0));
00200       else if (x0.min() > 0) GECODE_ME_CHECK(x0.eq(home,1));
00201       if (x0.assigned())
00202         return ((x0.val() == 0) || (x0.val() == 1))? home.ES_SUBSUMED(*this) : ES_FAILED;
00203     } else {
00204       GECODE_ME_CHECK(x0.eq(home,sqr(x1.val())));
00205       GECODE_ME_CHECK(x1.eq(home,sqrt(x0.val())));
00206       if (x0.assigned() || x1.assigned()) return home.ES_SUBSUMED(*this);
00207     }
00208 
00209     return ES_FIX;
00210   }
00211 
00212 }}}
00213 
00214 // STATISTICS: float-prop
00215