mirror of https://github.com/CGAL/cgal
266 lines
6.1 KiB
C++
266 lines
6.1 KiB
C++
// Copyright (c) 2005 Stanford University (USA).
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// All rights reserved.
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//
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// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public License as
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// published by the Free Software Foundation; version 2.1 of the License.
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// See the file LICENSE.LGPL distributed with CGAL.
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//
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// Licensees holding a valid commercial license may use this file in
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// accordance with the commercial license agreement provided with the software.
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//
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// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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//
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// $URL$
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// $Id$
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//
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//
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// Author(s) : Daniel Russel <drussel@alumni.princeton.edu>
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#ifndef CGAL_POLYNOMIAL_EXPLICIT_ROOT_H
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#define CGAL_POLYNOMIAL_EXPLICIT_ROOT_H
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#include <CGAL/Polynomial/basic.h>
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CGAL_POLYNOMIAL_BEGIN_INTERNAL_NAMESPACE
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//! a root that is represented explicitly
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/*!
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Not, the number type must have std::numeric_limits defined and
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infinity() or max() must be something reasonable. So exact types
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won't work at the moment.
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Coef_nt is the type of the polynomial coefficients, which can be disjoint from
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the root storage type, if desired. Not sure if this is useful as I am not sure
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you can get too far with an integer type for the coefficients, and anything
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else can be used to store the roots.
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*/
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template <class NT >
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class Explicit_root
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{
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typedef Explicit_root<NT> This;
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public:
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//! Set it to an invalid value
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Explicit_root(): value_(0), is_inf_(true), mult_(0){
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#ifndef NDEBUG
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approximation_=compute_double();
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#endif
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}
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template <class CNT>
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Explicit_root(const CNT &v, int mult=1): is_inf_(false), mult_(mult) {
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// Protect CORE::Expr from initialization with doubles (that is what this whole class is about anyway).
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if (std::numeric_limits<CNT>::has_infinity && CGAL::abs(v) == std::numeric_limits<CNT>::infinity()) {
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is_inf_=true;
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if (v > 0) value_=1;
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else value_=1;
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}
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else {
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value_= NT(v);
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}
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#ifndef NDEBUG
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approximation_=compute_double();
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#endif
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}
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//! Should be protected
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double compute_double() const
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{
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if (is_inf_) {
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if (CGAL::sign(value_)==CGAL::POSITIVE) {
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return infinity<double>();
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}
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else {
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return -infinity<double>();
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}
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}
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return CGAL_POLYNOMIAL_TO_DOUBLE(value_);
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}
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bool is_even_multiplicity() const
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{
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return mult_%2==0;
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}
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//! Do not use, should be protected
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std::pair<double, double> compute_interval() const
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{
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if (is_inf_) {
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return std::pair<double, double>(compute_double(), compute_double());
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}
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return CGAL_POLYNOMIAL_TO_INTERVAL(value_);
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}
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typedef NT Representation;
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const Representation &representation() const
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{
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return value_;
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}
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const Representation &to_rational() const
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{
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return value_;
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}
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template <class OS>
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void write(OS &out) const
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{
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if (is_inf_) {
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if (CGAL::sign(value_)==CGAL::POSITIVE) out << "inf";
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else out << "-inf";
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}
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else {
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out << value_;
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}
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}
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const std::pair<NT, NT>& isolating_interval() const
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{
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static std::pair<NT, NT> ret;
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ret= std::make_pair(value_, value_);
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return ret;
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}
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bool operator<(const This &o) const
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{
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return compare(*this, o)==-1;
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}
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bool operator>(const This &o) const
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{
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return compare(*this, o) ==1;
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}
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bool operator<=(const This &o) const
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{
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return compare(*this, o)!= 1;
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}
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bool operator>=(const This &o) const
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{
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return compare(*this, o) != -1;
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}
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bool operator==(const This &o) const
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{
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return compare(*this, o) ==0;
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}
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bool operator!=(const This &o) const
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{
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return compare(*this, o) !=0;
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}
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This operator-() const
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{
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return This(-value_, is_inf_);
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}
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int multiplicity() const
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{
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return mult_;
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}
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/*void write_type() const {
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std::cout << "general" << std::endl;
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}*/
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bool is_rational() const
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{
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// not really true
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return true;
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}
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static This infinity_rep() {
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return This(NT(1), true);
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}
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protected:
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static int compare(const This &a, const This &b) {
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int ret=0;
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if (a.is_inf_ && b.is_inf_) {
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if (CGAL::sign(a.value_)== CGAL::sign(b.value_)) ret= 0;
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else if (CGAL::sign(a.value_) == CGAL::POSITIVE ) ret= 1;
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else ret= -1;
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} else if (b.is_inf_) {
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CGAL_assertion(!a.is_inf_);
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if (CGAL::sign(b.value_)== CGAL::NEGATIVE) ret= 1;
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else ret= -1;
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} else if (a.is_inf_) {
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CGAL_assertion(!b.is_inf_);
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if (CGAL::sign(a.value_)== CGAL::NEGATIVE) ret= -1;
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else ret= 1;
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}
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else {
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if (a.value_ > b.value_) ret= 1;
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else if (b.value_ == a.value_) ret= 0;
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else ret= -1;
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}
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return ret;
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}
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Explicit_root(const NT &nt, bool isinf): value_(nt), is_inf_(isinf), mult_(1) {
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#ifndef NDEBUG
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approximation_=compute_double();
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#endif
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}
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NT value_;
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bool is_inf_;
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int mult_;
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#ifndef NDEBUG
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double approximation_;
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#endif
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};
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template <class NT>
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std::ostream &operator<<(std::ostream &out, const Explicit_root<NT> &r)
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{
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r.write(out);
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return out;
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}
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/*
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template <class NT>
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double to_double(const Explicit_root<NT> &r){
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return r.to_double();
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}
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template <class NT>
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std::pair<double, double> to_interval(const Explicit_root<NT> &r){
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return r.to_interval();
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}
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*/
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CGAL_POLYNOMIAL_END_INTERNAL_NAMESPACE
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CGAL_BEGIN_NAMESPACE
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template <class NT>
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double to_double(const CGAL_POLYNOMIAL_NS::internal::Explicit_root<NT> &r)
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{
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return r.compute_double();
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}
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template <class NT>
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std::pair<double, double> to_interval(const CGAL_POLYNOMIAL_NS::internal::Explicit_root<NT> &r)
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{
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return r.compute_interval();
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}
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CGAL_END_NAMESPACE
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namespace std
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{
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template <class Tr>
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class numeric_limits<CGAL_POLYNOMIAL_NS::internal::Explicit_root<Tr> >: public numeric_limits<Tr>
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{
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public:
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typedef numeric_limits<Tr> P;
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typedef CGAL_POLYNOMIAL_NS::internal::Explicit_root<Tr> T;
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static const bool is_specialized = true;
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static T min() throw() {return T(P::min());}
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static T max() throw() {return T(P::max());}
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static const bool has_infinity=true;
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static T infinity() throw() {return T::infinity_rep();}
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};
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};
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#endif
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