// Copyright (c) 2005 Stanford University (USA). // 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; either version 3 of the License, // or (at your option) any later version. // // 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(s) : Daniel Russel #ifndef CGAL_FIXED_POLYNOMIAL_INTERNAL_POLYNOMIAL_CORE_H_ #define CGAL_FIXED_POLYNOMIAL_INTERNAL_POLYNOMIAL_CORE_H_ #include #include #include #include #include #include #define CGAL_EXCESSIVE(x) namespace CGAL { namespace POLYNOMIAL { namespace internal { template class Fixed_polynomial_impl; template < class T, class NT, class C, class Tr, int D> inline std::ostream &operator<<(std::basic_ostream &out, const Fixed_polynomial_impl &poly); //! A basic polynomial class /*! This handles everything having to do with polynomials which is to not too numerically sensitive. The poly is stored as a vector. There are no 0 top coefficients in the vector. I don't store a value for 0 (there is not stored offset) since the polynomial will in general have to be recomputed when any certificate is computed, and I don't see any way of benefiting from delaying. If the STRIP_ZEROS flag is true then leading zeros are stripped on the fly. Otherwise you have to make sure that there are no leading 0s yourself. However, stripping leading 0s causes problems with an interval is used as the number type. */ //! todo: check resize and doubles template class Fixed_polynomial_impl { public: typedef NT_t NT; typedef const NT* iterator; typedef NT result_type; typedef NT argument_type; //================ // CONSTRUCTORS //================ //! Default Fixed_polynomial_impl() { for (unsigned int i=0; i<= D; ++i){ coefs_[i]=0; } } //! Make a constant polynomial Fixed_polynomial_impl(const NT& c) { for (unsigned int i=1; i<= D; ++i){ coefs_[i]=0; } coefs_[0]=c; //if (c != 0) degree_==0; //else degree_=-1; } //! Get coefficients from a vector template Fixed_polynomial_impl(Iterator first, Iterator beyond) { std::copy(first, beyond, coefs_); for (unsigned int i=static_cast(std::distance(first, beyond)); i<= D; ++i){ coefs_[i]=0; } } //======================== // ACCESS TO COEFFICIENTS //======================== //! Return the ith coefficient. /*! This must return a value for any value of i. */ const NT& operator[](unsigned int i) const { CGAL_assertion( i <= D); //if (i < coefs_.size()) { return coefs_[i]; /*} else { return zero_coef(); }*/ } //===================================== // ITERATORS FOR COEFFICIENTS //===================================== iterator begin() const { return coefs_; } iterator end() const { return coefs_+(std::min)(degree(), 0); } //========= // DEGREE //========= //! For the more mathematical inclined (as opposed to size()); int degree() const { for (int i=D; i>= 0; --i){ if (coefs_[i] != 0) return i; } return -1; } //============= // PREDICATES //============= //! Returns true if the polynomial is a constant function bool is_constant() const { return degree() < 1; } //! Returns true if f(t)=0 bool is_zero() const { return degree()==-1; } //======================= // OPERATORS //======================= //! negation This operator-() const { This ret; for (unsigned int i=0; i <= D; ++i) { ret.coefs_[i] = -coefs_[i]; } return ret; } //! polynomial addition This operator+(const This &o) const { This ret; for (unsigned int i=0; i<= D; ++i){ ret.coefs_[i]= coefs_[i]+ o.coefs_[i]; } return ret; } //! polynomial subtraction This operator-(const This &o) const { This ret; for (unsigned int i=0; i<= D; ++i){ ret.coefs_[i]= coefs_[i]-o.coefs_[i]; } //ret.finalize(); return ret; } //! polynomial multiplication This operator*(const This &o) const { CGAL_precondition(degree() + o.degree() <= D); This ret; for (unsigned int i = 0; i <= D; ++i) { for (unsigned int j = 0; j <= D-i; ++j) { NT prev = ret[i+j]; NT result = prev + operator[](i) * o[j]; ret.coefs_[i+j] = result; } } //ret.finalize(); //CGAL_EXCESSIVE(std::cout << *this << " * " << o << " = " << ret << std::endl); return ret; } //! add a scalar This operator+(const NT& a) const { This res(*this); res.coefs_[0] += a; //CGAL_EXCESSIVE(std::cout << *this << " + " << a << " = " << res << std::endl); return res; } //! subtract a scalar This operator-(const NT& a) const { return (*this) + (-a); } //! multiply with scalar This operator*(const NT& a) const { This res; for (unsigned int i = 0; i <= D; i++) { res.coefs_[i] = coefs_[i] * a; } return res; } //! divide by scalar This operator/(const NT& a) const { NT inv_a = NT(1) / a; return (*this) * inv_a; } //======================= // VALUE OF POLYNOMIAL //======================= //! Evaluate the polynomial at some value. /*! This is primarily for the solvers to call when they know the number type is exact. Note, this method performs a construction and is unreliable if an inexact number type is used */ NT operator()(const NT &t) const { if (is_zero()) return NT(0); else if (degree()==0 /* || t==NT(0)*/ ) { return operator[](0); } else { return evaluate_polynomial(coefs_, t); } } //! The non-operator version of operator() /*! */ NT value_at(const NT &t) const { return operator()(t); } //! !operator== bool operator!=(const This &o) const { return !operator==(o); } //! check if the coefficients are equal bool operator==(const This &o) const { for (int i = 0; i <=D; ++i) { if (o[i] != operator[](i)) return false; } return true; } void print()const { write(std::cout); } //! Read very stylized input template void read(std::basic_istream &in) { bool pos=(in.peek()!='-'); if (in.peek() == '+' || in.peek() == '-') { char c; in >> c; } char v='\0'; while (true) { char vc, t; NT coef; // eat in >> coef; if (in.fail()) return; unsigned int pow; char p= in.peek(); if (in.peek() =='*') { in >> t >> vc; if (t != '*') { in.setstate(std::ios_base::failbit); return; //return in; } if ( !(v=='\0' || v== vc)) { in.setstate(std::ios_base::failbit); return; //return in; } v=vc; p=in.peek(); if (in.peek() =='^') { char c; in >> c >> pow; } else { pow=1; } } else { pow=0; } if (pow > D) { in.setstate(std::ios_base::failbit); return; } if (!pos) coef=-coef; coefs_[pow]=coef; char n= in.peek(); if (n=='+' || n=='-') { pos= (n!='-'); char e; in >> e; } else { /*bool f= in.fail(); bool g= in.good(); bool e= in.eof(); bool b= in.bad();*/ // This is necessary since peek could have failed if we hit the end of the buffer // it would better to do without peek, but that is too messy in.clear(); //std::cout << f << g << e << b< void write(std::basic_ostream &out) const { std::basic_ostringstream s; s.flags(out.flags()); s.imbue(out.getloc()); s.precision(12); if (degree()==0) { s << "0"; } else { for (unsigned int i=0; i<= D; ++i) { if (i==0) { if (coefs_[i] != 0) s << coefs_[i]; } else { if ( coefs_[i] != 0 ) { if (coefs_[i] >0) s << "+"; s << coefs_[i] << "*t"; if (i != 1) { s << "^" << i; } } } } } out << s.str(); } /* typedef typename Coefficients::const_iterator Coefficients_iterator; Coefficients_iterator coefficients_begin() const { return coefs_.begin(); } Coefficients_iterator coefficients_end() const { return coefs_.end(); }*/ protected: //std::size_t size() const {return coefs_.size();} static const NT & zero_coef() { static NT z(0); return z; } //! The actual coefficients NT coefs_[D+1]; }; template < class T, class NT, class C, class Tr, int D> inline std::ostream &operator<<(std::basic_ostream &out, const Fixed_polynomial_impl &poly) { poly.write(out); return out; } template < class T, class NT, class C, class Tr, int D> inline std::istream &operator>>(std::basic_istream &in, Fixed_polynomial_impl &poly) { poly.read(in); return in; } //! multiply by a constant template inline T operator*(const NT &a, const Fixed_polynomial_impl &poly) { return (poly * a); } //! add to a constant template inline T operator+(const NT &a, const Fixed_polynomial_impl &poly) { return (poly + a); } //! add to a constant template < class T, class NT, int D> inline T operator+(int a, const Fixed_polynomial_impl &poly) { return (poly + NT(a)); } //! subtract from a constant template inline T operator-(const NT &a, const Fixed_polynomial_impl &poly) { return -(poly - a); } //! subtract from a constant template inline T operator-(int a, const Fixed_polynomial_impl &poly) { return -(poly - NT(a)); } } } } //namespace CGAL::POLYNOMIAL::internal #endif