March 2002 - PPL-devel - BUGSENG Mailman

NNC_minimize().
by Enea Zaffanella 28 Mar '02

28 Mar '02

Hi all. I just implemented a new method that performs the "strong" minimization of the systems of generators and constraints of an NNC_Polyhedron. This is based on a couple of rather simple observations that Elisa and I pointed out some time ago. The method is, for the moment, public and is named NNC_minimize(). I also added a few tests (named NNCminimize1-2-3) that seem to confirm the correctness of the approach. Surprisingly, my prototype implementation requires NO scalar product besides those computed in the standard minimization process (obviously, it does require some further adjacency tests, which are based on the already computed sat_c matrix). If the approach passes some more involved test, then we could start exploiting it where needed. In this sense, I still have to investigate whether or not the approach is applicable when we do NOT have some of the matrices minimized (e.g., what happens if con_sys is up-to-date but NOT minimized ?) ciao, Enea.

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ppl/src PolyBase.defs.hh
by Roberto Bagnara 28 Mar '02

28 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: roberto(a)cs.unipr.it 2002-03-28 16:46:43 Modified files: src : PolyBase.defs.hh Log message: Redeclared `shrink_bounding_box' as template <class Box> void shrink_bounding_box(Box& box) const; the previous declaration was too concrete. Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/PolyBase.defs.hh.diff?cvs…

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ppl/src PolyBase.defs.hh
by Roberto Bagnara 28 Mar '02

28 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: roberto(a)cs.unipr.it 2002-03-28 16:13:21 Modified files: src : PolyBase.defs.hh Log message: Added the declaration and documentation of template <class Interval> void shrink_bounding_box(std::vector<Interval>& box) const. Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/PolyBase.defs.hh.diff?cvs…

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ppl/tests Makefile.am NNCinclusion1.cc NNCmini ...
by Enea Zaffanella 28 Mar '02

28 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: zaffanella(a)cs.unipr.it 2002-03-28 15:42:30 Modified files: tests : Makefile.am Added files: tests : NNCinclusion1.cc NNCminimize1.cc NNCminimize2.cc NNCminimize3.cc Log message: Added a test on the inclusion method for NNC_Polyhedron and three tests for the full minimization of NNC_Polyhedron. Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/tests/NNCinclusion1.cc.diff?c… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/tests/NNCminimize1.cc.diff?cv… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/tests/NNCminimize2.cc.diff?cv… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/tests/NNCminimize3.cc.diff?cv… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/tests/Makefile.am.diff?cvsroo…

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ppl/src PolyBase.defs.hh PolyBase.cc
by Enea Zaffanella 28 Mar '02

28 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: zaffanella(a)cs.unipr.it 2002-03-28 15:40:30 Modified files: src : PolyBase.defs.hh PolyBase.cc Log message: Added method PolyBase::NNC_minimize() performing "full" minimization of constraint and generator systems of a NNC_Polyhedron. Temporarily public for testing and debugging purposes. Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/PolyBase.defs.hh.diff?cvs… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/PolyBase.cc.diff?cvsroot=…

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ppl/src Generator.cc
by Enea Zaffanella 28 Mar '02

28 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: zaffanella(a)cs.unipr.it 2002-03-28 15:37:14 Modified files: src : Generator.cc Log message: Printing closure points as c(lin-expr). Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/Generator.cc.diff?cvsroot…

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ppl/src ConSys.cc GenSys.cc
by Enea Zaffanella 28 Mar '02

28 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: zaffanella(a)cs.unipr.it 2002-03-28 09:53:54 Modified files: src : ConSys.cc GenSys.cc Log message: Methods get() and print() of classes ConSys and GenSys modified in order to: - read (and print) the new kinds of constraint/generators types; - check for the correspondence between declared and actual row types when reading them in; - check for the well-formedness of the read ConSys/GenSys, using OK(). Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/ConSys.cc.diff?cvsroot=pp… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/src/GenSys.cc.diff?cvsroot=pp…

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Questionable feature of the C++ interface (GMP 4.0.1)
by Roberto Bagnara 27 Mar '02

27 Mar '02

After a rather difficult debugging session I discovered a feature of the C++ interface shipped with GMP 4.0.1 that is rather questionable. The problem is exemplified by the following snippet: ////////////////////////////////////////////////////////////////////////// #include <gmpxx.h> typedef struct any_thing* any_pointer; any_pointer bar(); void foo() { //int i = bar(); // This is flagged as an invalid conversion... mpz_class n = bar(); // ... but this one is happily accepted! } ////////////////////////////////////////////////////////////////////////// As you see, a pointer is erroneously used to initialize an mpz_class object, but this is not and cannot be flagged by the compiler, not even as a warning. The reason is that <gmpxx.h> has a constructor defined as __gmp_expr(bool b) { mpz_init_set_ui(mp, b); } and the C++ standard specifies (clause 4.1.2, [conv.bool]) that An rvalue of arithmetic, enumeration, pointer, or pointer to member type can be converted to an rvalue of type bool. A zero value, null pointer value, or null member pointer value is converted to false; any other value is converted to true. So what happens is that a pointer is converted to true or false and then converted to 1 or 0 and this is what is used to initialize the object. Since this can give rise to bugs that are quite difficult to diagnose, I propose the above constructor is removed altogether, so that the compiler can complain loudly. Notice that qualifying that constructor as `explicit' would not be enough as mpz_class n = bar(); would be flagged as an error, but mpz_class n(bar()); would be happily accepted. Removing the constructor would not cause a significant loss in functionality since the rare cases where one wants to do such a thing can be handled in several ways, most of which are more readable and faithful to the actual intention that the examples above. I have mailed this message to the present list and not to bug-gmp because a) strictly speaking, this is not a bug; b) other users may benefit from this information. All the best Roberto -- Prof. Roberto Bagnara Computer Science Group Department of Mathematics, University of Parma, Italy http://www.cs.unipr.it/~bagnara/ mailto:bagnara@cs.unipr.it

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ppl NEWS TODO
by Roberto Bagnara 27 Mar '02

27 Mar '02

CVSROOT: /cvs/ppl Module name: ppl Changes by: roberto(a)cs.unipr.it 2002-03-27 19:22:25 Modified files: . : NEWS TODO Log message: Updated. Patches: http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/NEWS.diff?cvsroot=ppl&r1=1.18… http://www.cs.unipr.it/cgi-bin/cvsweb.cgi/ppl/TODO.diff?cvsroot=ppl&r1=1.18…

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ppl ./TODO interfaces/C/ppl_c.cc interfaces/Pr ...
by Roberto Bagnara 27 Mar '02

27 Mar '02

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