cgal/Algebraic_kernel_d/include/CGAL/RS/solve_1.h

// Copyright (c) 2006-2009 Inria Lorraine (France). All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
// Author: Luis Peñaranda <luis.penaranda@loria.fr>

#ifndef CGAL_RS_SOLVE_1_H
#define CGAL_RS_SOLVE_1_H

#include <CGAL/basic.h>
#include <CGAL/RS/basic.h>
#include <gmp.h>
#include <mpfr.h>
#include <mpfi.h>
#include <CGAL/RS/dyadic.h>
#include <CGAL/RS/solve_1.h>
#include <CGAL/RS/polynomial_1.h>
#include <CGAL/RS/algebraic_1.h>
#include <rs_exports.h>

namespace CGAL{

class RS_polynomial_1;
class Algebraic_1;

#define CGALRS_CSTR(S) ((char*)(S))

// initialize RS solver
inline void init_solver(){
        static bool first=true;
        if(first){
                first=false;
                //rs_version(stderr);
                rs_init_rs();
                rs_reset_all();
        }
}

// reset RS memory
inline void reset_solver(){
        rs_reset_all();
}

inline int affiche_sols_eqs(mpfi_ptr *x){
        int ident_sols_eqs,nb_elts,ident_node,ident_vect,ident_elt,i;
        ident_sols_eqs=rs_get_default_sols_eqs ();
        nb_elts=rs_export_list_vect_ibfr_nb(ident_sols_eqs);
        ident_node=rs_export_list_vect_ibfr_firstnode(ident_sols_eqs);
        //x=(mpfi_ptr*)malloc(nb_elts*sizeof(mpfi_ptr));
        for (i=0; i<nb_elts; ++i) {
                ident_vect=rs_export_list_vect_ibfr_monnode(ident_node);
                CGAL_assertion_msg(rs_export_dim_vect_ibfr(ident_vect)==1,
                                "the dimension of vector must be 1");
                ident_elt=rs_export_elt_vect_ibfr(ident_vect,0);
                x[i]=(mpfi_ptr)rs_export_ibfr_mpfi(ident_elt);
                ident_node=rs_export_list_vect_ibfr_nextnode(ident_node);
        }
        return nb_elts;
}

inline void affiche_sols_constr(int nr,mpfi_ptr p){
        int ident_sols_eqs,nb_elts,ident_node,ident_vect,nb,ident_elt;
        ident_sols_eqs=rs_get_default_sols_ineqs();
        nb_elts=rs_export_list_vect_ibfr_nb(ident_sols_eqs);
        ident_node=rs_export_list_vect_ibfr_firstnode(ident_sols_eqs);
        for(int i=0;i<nb_elts;++i){
                ident_vect=rs_export_list_vect_ibfr_monnode(ident_node);
                nb=rs_export_dim_vect_ibfr(ident_vect);
                CGAL_assertion_msg((nb==1),
                                "the vector must contain one element");
                ident_elt=rs_export_elt_vect_ibfr(ident_vect,0);
                if(i==nr){
                        mpfi_set(p,(mpfi_ptr)rs_export_ibfr_mpfi(ident_elt));
                        //break;
                }
                ident_node=rs_export_list_vect_ibfr_nextnode(ident_node);
        }
}

inline Sign affiche_signs_constr(const Algebraic_1 &a){
        int ident_sols_eqs,nb_elts,ident_node,ident_vect, nb, ident_elt;
        mpfi_t tmp;
        mpfi_init(tmp);
        ident_sols_eqs = rs_get_default_sols_ineqs ();
        nb_elts = rs_export_list_vect_ibfr_nb (ident_sols_eqs);
        ident_node = rs_export_list_vect_ibfr_firstnode (ident_sols_eqs);
        for (int i=1; i<nb_elts+1; ++i) {
                ident_vect = rs_export_list_vect_ibfr_monnode (ident_node);
                nb = rs_export_dim_vect_ibfr (ident_vect);
                CGAL_assertion_msg ((nb == 1),
                                "the vector must contain one element");
                ident_elt = rs_export_elt_vect_ibfr (ident_vect, 0);
                if (i == a.nr()+1) {
                        mpfi_set(tmp,(mpfi_ptr)rs_export_ibfr_mpfi(ident_elt));
                        break;
                }
                ident_node = rs_export_list_vect_ibfr_nextnode (ident_node);
        }
        //std::cerr << "\nreturned value: ";
        //mpfi_out_str(stderr,10,0,tmp);
        //std::cerr << std::endl;
        // mpfi_is_zero(tmp) doesn't work. The reason is that MPFR_SIGN in
        // the mpfi code returns 1 when applied to the left and right zeros.
        // This is not surprising because zero is signed in IEEE 754, and MPFR
        // adopts it. Nevertheless, mpfr_sgn returns 0, but mpfi doesn't use
        // it to implement mpfi_is_zero.
        // Here is the difference (from MPFR source code):
        //  define mpfr_sgn(_x)      (mpfr_zero_p(_x) ? 0 : MPFR_SIGN(_x))
        //
        if(mpfr_zero_p(&(tmp->right))&&mpfr_zero_p(&(tmp->left)))
                return ZERO;
        // the same holds for mpfi_is_pos and mpfi_is_neg
        if((mpfr_sgn(&(tmp->left))>=0)&&(mpfr_sgn(&(tmp->right)))>0)
                return POSITIVE;
        if((mpfr_sgn(&(tmp->left))<0)&&(mpfr_sgn(&(tmp->right))<=0))
                return NEGATIVE;
        // if we arrive here, it is because the signs of the endpoints are -
        // and +, and (I think) RS guarantees that this never happens
        CGAL_assertion_msg(false,"error in sign calculation");
        return ZERO;
}

inline void create_rs_upoly (mpz_t *poly, const int deg, const int ident_pol) {
        int ident_mon, ident_coeff, i;
        rs_import_uppring(CGALRS_CSTR("T"));
        for (i=0; i<=deg; ++i)
                if (mpz_sgn (poly[i]))  {       // don't add if == 0
                        ident_mon = rs_export_new_mon_upp_bz ();
                        ident_coeff = rs_export_new_gmp ();
                        rs_import_bz_gmp
                                (ident_coeff, TO_RSPTR_IN (&(poly[i])));
                        rs_dset_mon_upp_bz (ident_mon, ident_coeff, i);
                        rs_dappend_list_mon_upp_bz (ident_pol, ident_mon);
                }
}

inline void create_rs_uconstr (mpz_t ** list_constr,
                const int * list_degs, const int ident_list) {
        int ident_poly;
        ident_poly = rs_export_new_list_mon_upp_bz ();
        create_rs_upoly (*list_constr, *list_degs, ident_poly);
        rs_dappend_list_sup_bz (ident_list, ident_poly);
}

// solve given the precision, returns the number of roots
inline int solve_1(
                   mpfi_ptr *x,
                   const RS_polynomial_1 &p1,
                   unsigned int prec=CGAL_RS_DEF_PREC){
        rs_reset_all();
        create_rs_upoly(p1.get_coefs(),p1.get_degree(),rs_get_default_up());
        set_rs_precisol(prec);
        set_rs_verbose(CGAL_RS_VERB);
        rs_run_algo(CGALRS_CSTR("UISOLE"));
        return affiche_sols_eqs(x);
}

// calculate the sign of a polynomial evaluated at the root of another
inline Sign sign_1_rs(
                      const RS_polynomial_1 &p1,
                      const Algebraic_1 &a,
                      unsigned int prec=CGAL_RS_MIN_PREC){
        mpz_t **constr;
        int *degs;
        CGAL_assertion(a.is_consistent());
        rs_reset_all ();
        // tell RS to find the roots of this polynomial
        create_rs_upoly (a.pol().get_coefs (), a.pol().get_degree (),
                        rs_get_default_up ());
        // the constraint vector will have just one element
        constr = (mpz_t**)malloc(sizeof(mpz_t*));
        *constr = p1.get_coefs ();
        degs = (int*)malloc(sizeof(int));
        *degs = p1.get_degree ();
        create_rs_uconstr (constr, degs, rs_get_default_ineqs_u ());
        set_rs_precisol (prec);
        set_rs_verbose (CGAL_RS_VERB);
        rs_run_algo(CGALRS_CSTR("UISOLES"));
        //Sign s=affiche_signs_constr(a);
        //std::cout<<"sign of "<<p1<<" in the root of "<<a.pol()<<" = "<<s<<std::endl;
        //return s;
        return affiche_signs_constr (a);
}

} // namespace CGAL

#endif  // CGAL_RS_SOLVE_1_H

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